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dikman
01-16-2014, 06:02 AM
I've been doing lots of reading about PIDs, and trying to convince myself that I don't need one (actually, I don't really need one, but it looks like an interesting little project). Has anyone built one using a relay instead of an SSR? I realise that both methods have their advantages/disadvantages, but so far everyone here seems to have used an SSR, and I got curious.

6bg6ga
01-16-2014, 07:24 AM
To answer your question I have built a setup using a relay instead of a solid state relay and it works fine. Both have their pros and cons. A relay will require its own power supply to energize the coil of the relay and the contacts need to be rated high enough to carry the current. With the SS relay they develop a lot of heat and that heat needs to be heat sinked in order to get rid of the heat and not have heat build up in the electrical box that you install it into.

With the external relay setup your going to use the small relay inside the PID to run the voltage (one leg) that your going to send to the external relay coil. In other words your using the PIDS small internal relay to control the external relay. With the SSR the PID has to send a control signal (small voltage 3-32VDC) to the SSR and the SSR acts like a switch to turn on/off the AC to the load.

6bg6ga
01-16-2014, 07:29 AM
Probably the main reason for people to use a SSR is they are simple to wire and take no skill level to put together. Kind of like buying an amplifier in a kit and putting it together..no math involved and everything solved for you.

When selecting PIDs the cheapest and not necessarily the best is the MYPIN and a nice step up is the Auber and from there the industrial units provide better control and programing options some from a laptop.

texassako
01-16-2014, 10:36 AM
Mechanical relays are only rated for 100k switches or so. The SSR will last a lot longer when you consider how often it is going to be switching.

lancem
01-16-2014, 11:08 AM
Limited life, arcing and burning of contacts along with the other things mentioned above are reasons you don't see mechanical relays in industrial settings anymore. SSR are less maintenance in the long run, typically cheaper than a properly sized mechanical relay.

leadman
01-16-2014, 11:43 AM
I've built 3 of them and used vented boxes I bought off E-bay. I mounted the SSR to the inside bottom of the boxes and have had no heat issues. The first one has been in almost daily use since spring and thru the Arizona summer.
If you look on e-bay you can by the pid, ssr, and thermocouple together for a very reasonable price.
I didn't want the probe inside my pot so I rethreaded a t-nut to the 6mm thread for the thermocouple and brazed it to the bottom of my RCBS pot. Works great.

6bg6ga
01-16-2014, 06:30 PM
Limited life, arcing and burning of contacts along with the other things mentioned above are reasons you don't see mechanical relays in industrial settings anymore. SSR are less maintenance in the long run, typically cheaper than a properly sized mechanical relay.

You haven't seen many machines I take it. Some are still equipped with mechanical relays.

With respect to the 100K cycle life. I've seen relays exceed this 100K by 5X before needing a relay changed. I've personally run a few machines and put a few 100K cycles thru them.

6bg6ga
01-16-2014, 06:52 PM
dikman

I've been trying to stay with the spirit of your thread so lets recap for a second before this turns into 50 people ranting about using an SSR and a relay is junk.

Relays don't last forever they have a life and that life can and usually does exceed 100K per my experience.

Relays are costly because you need contacts rated for your load.

Relays require a separate power supply

Relays require a little more wiring

SSR's are cost effective

SSR's need to be heat sinked and or have adequate venting inside the box.

SSR's are childishly simple to wire

There you have most of the information you need for you to make your decision.


My >02 just for grins.

My Ballisti-cast Mark IV uses a SSR and I kept it because of the current draw on the pot heaters.

One of my Sizer heaters is run with a PID/relay setup simply because I had the parts on hand and the load is small on the heater (4 Amp)

My first sizer heater PID setup used a SSR which I consider over kill.

taiden
01-16-2014, 07:11 PM
Everything has pretty much been covered. To me the biggest difference is a SSR can flicker on and off hundreds of times in a second, thus allowing the PID controller to adjust the percentage of time on, so the heating coil will literally stay at the exact temp. With a relay, the switching time is usually suggested to be between 10 seconds and 30 seconds because of the lifespan. So you can be going full bore for those 10-30 seconds, and then off for however long... In the end it will work far better than just about any other method of heat control, but with much less finesse.

Frozone
01-16-2014, 07:25 PM
Lets recap since you have been receiving erroneous information. (and in 2 posts at a time)

If you buy a relay output controller (Auber SYL-2342 or a Mypin TA4-Rxx are examples) to start with, they will run Most pots as is.

There are advantages and disadvantages to either a relay or a SSR output.

Heat: Both relays and SSRs generate heat while operating. Relays have a almost constant wattage for a given duty cycle while in a SSR the wattage is load based.
Relays can switch at the max rating without any (or at least much) change in heat produced, the SSR will produce more heat as the wattage through it increases.
Relays are hard to heat sink, SSRs are rather easy to sink but require extra space for the sink.

Life Expectancy:
Both Relays and SSRs have a life expectancy.
Most mechanical relays have a dual rating; So many cycles mechanically and so many electrically.
Often the 100K operations for the contact life ( there are a few thing that matter here),
and likely a million or more cycles mechanically. (that is the actual moving parts). Contact life depends on current, voltage (same thing really), and what is being switched,
also how that circuit is designed. Vibration, humidity, and dust also have an effect on mechanical relay life.
Keep the current low and switch non inductive/capacitive loads and you can get Much greater than rated contact life.
SSRs are fairly immune to reasonable levels of vibration, dust, and humidity. They are susceptible to current surges, over voltages, heat, and radiation.


Operation:
SSRs don't require much current to operate the control side and want DC voltage for the curcuit - this simplifies the design of the controller.
If you need a high current relay, you will need to find a way to drive a rather current hungry device.
Getting that current out of the cheap controllers is not possible, Most can only supply < 100mA.
A far as wiring it up, the internal Relay units are simpler to wire because all the control lines are internal to the controller only 1 extra wire needs to be run to the controller.
With a SSR you must run AC to the SSR and also 2 control lines from the controller.

Summary:
Both SSRs and relays are a viable option.
But, the SSR has advantages if there is room to use it.

taiden
01-16-2014, 07:39 PM
Your explanation was very thorough from a design point of view but you skipped over the part the user will notice during use. SSRs allow the PID controller to utilize pulse-width modulation to control the heat of the element which has a response time slower than the period of the "pulse". This allows it to maintain exact temperature at the heating element.

A relay (by it's mechanical nature) will not gracefully handle the switching frequency required for PWM control. Most PID controller's documentation suggest a 10-30 second period when using a mechanical relay, and as such the relay will attempt to average the heat input over this longer period.

dikman
01-16-2014, 07:55 PM
6bg6ba, thanks mate, that's what I wanted, someone who has actually done it. Nicely summarized, btw.

I should clarify that I've spent a lifetime in electronics (starting with valves!) so I understand the pros and cons of SSR's vs relays. The relay option would actually be cheaper to build, and fitting a small transformer and bridge rectifier in the case would take care of the power supply for the relay without needing an external plugpack. My RCBS runs on 230v and only draws 3.5 amps so relay rating isn't much of an issue. The relays I've looked at are rated to 200K operations, so again not an issue.
Taiden does raise a valid point about the switching time, but I really don't think it's an issue in this case as I doubt it's necessary when melting lead to keep it to such tight tolerances.

There is one potential issue with SSR's that I can see - they run hot. The primary cause of failure of electronic devices is heat, that is arguably their one weakness, and if they fail may do so in the "on" position (unlike a relay). Not a problem as long as you still have the original thermostat connected on the device, I guess. I suppose I'll now get inundated with people saying how reliable SSR's are, and they probably are, but NO electronic component can be guaranteed fail-safe. Just sayin'.

Other than a PID (which will probably cost about $20-25) I should have everything else on hand (somewhere, just got to find it!) to build a relay version. I have a 1000C thermocouple on the way, for the princely sum of $6. Like I said, I don't need one, but it's looking more and more like an interesting little (and cheap) project.

taiden
01-16-2014, 07:59 PM
I'd love to see what you come up with. I have a PID and SSR from an old toaster project. That's going on my little 10# lee pot eventually. :)

Frozone
01-16-2014, 08:51 PM
The relay option would actually be cheaper to build, and fitting a small transformer and bridge rectifier in the case would take care of the power supply for the relay without needing an external plugpack.

It will be cheaper.

But why do you want a "small transformer and bridge rectifier"??? by the time you get that in there you might as well use the SSR.

The controllers are available with relays in them that handle 10A, more than enough for your pot.

Or are you going to buy an SSR output controller to run an External relay?
Or worse an internal relay controller to run an external relay?

( I put the last line in a PM to you.)

Mal Paso
01-16-2014, 10:07 PM
It's not like SSRs produce a lot of heat.

SSRs produce about 1.3 watts of heat for every amp controlled when it is on. About 8 watts for a Lee 4-20. Bolting it to the inside of a metal cabinet is usually enough.

Leaving the thermostat in the loop with a will interfere with a PID, especially with the Lee. They need to be set to max or bypassed.

dikman
01-17-2014, 01:02 AM
Thanks guys, this discussion will hopefully be useful for anyone else who considers this option.

Mal, I realise that the thermostat must be set on max, if left in the cct. I just omitted to mention it [smilie=1:.

Frozone, I haven't seen any PIDs (so far) that can handle the pot amperage via their inbuilt relay (although I'm not sure I'd really want to do it that way anyhow, I'd much prefer that sort of current not go via the PID). If it was that simple why does everyone use an SSR?

Frozone
01-17-2014, 04:26 AM
If it was that simple why does everyone use an SSR?

If the relay was superior to the electronic switch for controlling 'trons we'd all be using ENIACs instead of PCs. ;-)
The SSR is the simplest most reliable way to switch AC with a DC signal.

The current to the internal relay only goes < 1/4" to the relay pins and the same or less back out.
The relay in a Mypin TA4 is a 5A @250V/10A @120V rated device.

The Main relay in the Auber is rated to 10A 110V ( I'm not sure I believe em however), the alarm relays are only 2A .

The wear on the contact points switching a purely resistive load is minimal compared to an inductive load.
But ALL relays contact will wear out. It's the arc as the contact break the circuit. It eventually eats the contact away.

One option is n SSR output running a relay. Internal SSR controllers are available. They have a low current rating (< 2A) because of heat problems.
They can be had to replace small relays on circuit boards. They need no external sinks and don't add to the size.
That would easily run a AC coil power relay for your pot.

Best of both worlds.
Because it's switching 250mA or less, the SSR is small and cool and not likely to burn out as it has a rather high resistance load in the relays coil.
The relay is external to the controller and can be replaced easy if it need attention.

dikman
01-17-2014, 05:48 AM
By simple I was referring to the possibility of using the PID internal relay - if it can handle the load why bother with any external switching (either relay or SSR)? Not that I'm interested in doing that, I prefer to keep the main heavy current switching, and the most likely source of failure imo, outside the PID. As you say, it's much easier to get to if there's a problem with it.

This all came about because I have everything I need, electronically speaking, to build one with a relay (so very cheap to do). However, while discussing this earlier I thought I should work out the current drain of the pot and when I realised it was only 3.5 amps I figured that even an over-rated 25 amp SSR should barely get warm at that rate (plus the 25 amp units are dirt cheap!). So, bearing in mind that using an SSR is the simplest way to do it (as Frozone has pointed out), and I would be creating more work for myself for the sake of less than $5, it seems I have now rationalised why I should use an SSR and not a relay. :grin:.

That's one of the things I like about forums, they give you a chance to bounce ideas off people and get your thoughts in order (sort of, in my case).

6bg6ga
01-17-2014, 07:26 AM
By simple I was referring to the possibility of using the PID internal relay - if it can handle the load why bother with any external switching (either relay or SSR)? Not that I'm interested in doing that, I prefer to keep the main heavy current switching, and the most likely source of failure imo, outside the PID. As you say, it's much easier to get to if there's a problem with it.

This all came about because I have everything I need, electronically speaking, to build one with a relay (so very cheap to do). However, while discussing this earlier I thought I should work out the current drain of the pot and when I realised it was only 3.5 amps I figured that even an over-rated 25 amp SSR should barely get warm at that rate (plus the 25 amp units are dirt cheap!). So, bearing in mind that using an SSR is the simplest way to do it (as Frozone has pointed out), and I would be creating more work for myself for the sake of less than $5, it seems I have now rationalised why I should use an SSR and not a relay. :grin:.

That's one of the things I like about forums, they give you a chance to bounce ideas off people and get your thoughts in order (sort of, in my case).

You asked for Pros and Cons and that is what I tried to give you. I also pointed out that I had the necessary parts on hand to use an external relay in a specific application that I had. Your right the SSR is simple to use and you don't have to be literate to use it. Care however is needed when switching a 20A load for example because of the heat build up from the SSR. The large loads, small electrical enclosures, inedaquate heat sinking/cicrulation will kill your PID. When exposed to the conditions I listed the PID will simply go off/blank and come back on and repeat this cycle until it dies.

I had purchased a piece of equipment that uses a Mypin and 25A SSR. It ran a full day and about three hours into the second day before the PID started turning on and off. IR thremometer scan revealed internal temps in excess of 125degrees in the box. The SSR was bolted to the electrical box with no heat sinking. I solved the problem with the addition of heat sinking, a power supply, and fan. So, one must also exercise caution when mounting the electrical enclosure close if not next to a heat source.

Unlike others.... I have no dog in the fight.

6bg6ga
01-17-2014, 08:28 AM
93740
93741
93739

Pictures of a Mypin PID relay with the cover removed. Cover says 10A/125vac, 5A 250, 5A 30vdc.

The problem with a lot of stuff coming out of china lately is this.... sometimes their a cheap copy of another product or a the ratings cannot be trusted.

Ten amps at 125VAC? I don't think so. The contact portion of the relay only measures .070 for width which is in line for a product made here in the states with a 3A rating. Ten amps for this relay is WAY overstated in my opinion.

dikman
01-18-2014, 03:01 AM
No argument from me, 6bg. I'm familiar with those PC mount relays, and there's no way I'd run the main feed through the internal relay contacts, I'd only use it for switching an external relay (with decent contacts on it). I've been talking about those "ice cube" type relays, btw, I have a couple (Siemens) that are rated at 240v/10A. In the "old days", when components were manufactured in the US, UK, Germany, Japan - even here in Oz - their ratings were generally conservative. These days I wouldn't consider many of the components coming out of China to be rated on the conservative side. There are some factories there that do make good stuff, but there are many where the only concern is to make it/sell it as cheap as possible (and they're often somewhat "loose" when describing their products' capabilities, I've noticed).

Anyhow, I figure that even if a 25A SSR is over-rated by 25%, that still leaves me with a hefty margin if only switching 3-4A. Thanks for your input, it's been most useful.

el34
01-18-2014, 12:44 PM
If relays were better for this application than SSRs, we'd all be buying relays.

6bg6ga
01-18-2014, 01:55 PM
If relays were better for this application than SSRs, we'd all be buying relays.


Start from the beginning and read this thread over again. No one is saying relays are better. What has been discussed are the pros and cons of both.

Dale in Louisiana
01-18-2014, 02:53 PM
It will be cheaper.

But why do you want a "small transformer and bridge rectifier"??? by the time you get that in there you might as well use the SSR.

The controllers are available with relays in them that handle 10A, more than enough for your pot.

Or are you going to buy an SSR output controller to run an External relay?
Or worse an internal relay controller to run an external relay?

( I put the last line in a PM to you.)

You don't NEED a small transformer and rectifier IF your controller's contact outputs are rated for your power supply.

I do this all the time in an industrial environment. I use a wide variety of relays suitable for load currents of anywhere from fractions of an amp to HUNDREDS of amps and voltages from 5 vDC to 5 kV. (Okay, that last one is called a medium voltage contactor, but it operates at 120 vAC).

Choose your relay based on load current and voltage. You want something that will switch ten amps at 120 VAC. These are common as mud. And you want one with coil voltage at 120 vAC. Again, common as mud.

In industrial applications with which I work daily, solid state relays are not common electromechanical relays are.

And one thing I didn't see mentioned about a possible plus for the electromechanical relay is that you can normally hear it pick up and drop out, so you know your controller is working.

dale in Louisiana
(this week it was 771 kW at 480 volts. Like working on a watch)

el34
01-18-2014, 03:08 PM
Start from the beginning and read this thread over again. No one is saying relays are better. What has been discussed are the pros and cons of both.

You're totally right, no argument here. I'm also an EE and understand the pros/cons, all I meant to do was point out the obvious.

dikman
01-19-2014, 12:36 AM
Dale, hearing a relay dropping in/out had occurred to me, I just didn't bother mentioning it (I wondered if anyone else would). I too grew up around relays, although not of the capacity you work with! There is something "re-assuring" about hearing a relay operating :grin:.

The reason I mentioned the internal transformer to drive an external relay is because none of the PID's I've been looking at are rated higher than 3A via the internal relay contacts. I could probably replace the internal relay with a higher rated one, but
a) I can't be bothered and
b) I'd rather not have 230v switching within the PID

If it decided to go belly-up, for whatever reason, it quite possibly would render the PID itself unusable. Much better to have that sort of switching, whether by relay or SSR, external to the PID. Easier to get to, and if the switching died it shouldn't affect the PID.

Actually, el, even if relays were better I suspect that most would still use SSR's, as Frozone pointed out they are more convenient to use and simplify the circuitry (which also makes things slightly safer, particularly for those who aren't too conversant with electrics/electronics - something I think you will probably understand).

6bg6ga
01-19-2014, 07:13 AM
Good points

I personally like hearing a relay drop in and out. I would guess that 99.9% of the people don't like or don't understand relays. When faced with having a PID on hand with no control voltage output in order to run a SSR I am perfectly at home using a external relay and using the internal relay to switch it. I'm not comfortable using 230volts and having it switch via the internal relay. My pictures of the MYPIN's internal relay contact points do show the relay isn't a 10A/250volt relay. The relay points are less that 1/2 the size of a trusted relay that is rated at 7A. So you be your own judge on this. The SSR's are easy for the child at heart and don't require any thought and this is why Frozone makes money selling his little kit. His kit works, no one has to come up with a box and the wiring has been done.

Like I pointed out this thread is not to deceide which is better as we certainly don't need 3000 members each telling that they like their SSR. Who gives a rats ear? The point is that questions were asked if anyone had used a relay and these questions have been answered.

Both the relay and the SSR will work fine............................

Frozone
01-19-2014, 10:03 AM
Well, you do realize that you're going to be sending 230V into the PID anyway.

"Frozone pointed out they are more convenient to use and simplify the circuitry"
And actually, I pointed out the Opposite, The internal relay is the simplest of the options to wire.

6bg6ga
01-19-2014, 03:39 PM
If we can trust the specifications of the MYPIN PID it is rated 90-260v AC/DC input voltage.


The internal relay however is another story and its ratings cannot be trusted. I believe the poster had misgivings when trusting the internal relay to switch the 220-240 v AC line voltage.

In examining the relay myself I found its contacts 1/2 the size of a 7A Japaneese relay that I happen to stock. Which makes it more in line to be a 3A relay not a 10A one.

dikman
01-19-2014, 07:23 PM
Ok, you're correct, Frozone, in that from a purely practical aspect using the internal relay is the simplest method (assuming that the relay has sufficient rating). My apologies for mis-quoting you. However, being able to do it in theory is one thing, actually doing it in practice is another issue entirely. I have learnt, over the years, to be very cautious about building ccts. using 230v AC mains, and switching it inside the PID, via a tiny PC mount relay of questionable rating is not what I (at least) consider good practice. Besides, other than the Mypin every other PID I've looked at has the relay rated at 3A, which is clearly not enough.

230v going into the PID to operate it is one thing, but as 6bg said, switching 230v via the internal relay is something I'm just not comfortable with.

So, a cheap 25A SSR is on it's way, as is a (non-Mypin) PID - about 1/2 the price of a Mypin - along with a 1000C K-probe. All up, about $30. As I've mentioned, it's not something that I need, but after all this talk about them I've just got to build one!!!
I can't help myself......

6bg6ga
01-19-2014, 08:18 PM
Mr. Frozone,

In response to the PM you sent me. Please have someone read post #20 to you and you will see that I do indeed have the correct rating on your MYPIN PID. That would be 10A/125vac, 5A/250vac.

Please do not send me any more vulgar PM"S.

Frozone
01-19-2014, 08:34 PM
......Besides, other than the Mypin every other PID I've looked at has the relay rated at 3A, which is clearly not enough........as is a (non-Mypin) PID - about 1/2 the price of a Mypin............

Well the Auber units are rated 10A@120V/5A@250V but if you don't like the Mypin price then you won't like that cost!
Where did you find a 48mm square controller for $12? Mypins run under $25.

I think You have made the right choice, as far as the SSR, in this application they are a good choice (actually in Most if not all apps).
Just be sure that low priced unit is capable of all you need, read the specs carefully.

I certainly understand wanting one - the darn things are addictive!

dikman
01-20-2014, 12:48 AM
It's an XMT800 (just over Aus $20). The Mypins were a bit under Aus $40 (out of Hong Kong, even dearer in Oz!), if I saw one for $25 I would have grabbed it! I went slightly cross-eyed reading specs. The XMT's are also available with bigger displays, for not much more money, but the smaller size should make a neater package overall. All these bits are generally cheaper out of China, but shipping from there is a lot slower than from HK.

If you want cheap, how about a Rex-C100 for Aus$13? (from HK, cheapest I've seen yet, only problem is they're relay output).
Or a package deal - Rex-C100, 40A SSR and 400*C probe for Aus $19 ex-HK? Of course, I'm not sure how the SSR is supposed to work with relay o/p, and the probe is a short screw-mount type. But for that price I'm sorely tempted just to have a play with it.
http://www.ebay.com.au/itm/100-240V-Digital-PID-Temperature-Controller-max-40A-SSR-K-Thermocouple-Probe-/121249215334?pt=AU_B_I_Electrical_Test_Equipment&hash=item1c3b043366

Edit: I just looked at the manual for the Rex-C100, and it seems that they may do a model with SSR o/p. Only way to find out is to try and work out the code for the model no.

6bg6ga
01-20-2014, 07:44 AM
dikman

At this time your supposed to drop down on one knee and purchase Frozones complete PID package. After all he is the only one that knows absolutely everything about PIDs and electronics.

How dare you even think of purchasing Aubor or anything off ebay for that matter.

el34
01-20-2014, 05:44 PM
dikman

At this time your supposed to drop down on one knee and purchase Frozones complete PID package. After all he is the only one that knows absolutely everything about PIDs and electronics.

How dare you even think of purchasing Aubor or anything off ebay for that matter.

So dikman, you're the original owner of the post. I'm hoping you got some good stuff out of it! Whichever way you go, I'll bet you'll enjoy it, you seemed excited about it.

Bill

dikman
01-20-2014, 08:17 PM
Ahh, 6bg, there's no doubt about it, you're a very funny man [smilie=l:. If that's the case then I've failed miserably. Although I've built kits in the past, I usually make my own PC boards, where possible, buy what components I don't have (and I've accumulated a lot of stuff over the years) and build things myself.
As for ebay, it's been a godsend for those of us living in Oz. We've been ripped off for years when it comes to buying things and ebay is now starting to level the playing field somewhat.

Bill, yep, it's been a good thread. Lots of info, and it's helped me get a better grasp on something I knew nothing about - PID's, and what makes them tick. I have no qualms about using a relay (heck, the early automatic telephone exchanges I built/worked on were basically nothing but relays and relay switches - just an awful lot of them!). In fact, that's what I intended doing until I realised that at 230v the pot's using half the current that most of you guys were talking about, so an el cheapo SSR is all I need, and will probably barely get warm. Anything heavier and I would have given serious thought to using relays.

Excited isn't quite the word I'd use. I just enjoy building/making stuff for my hobbies, and this is simply an excuse to build something new, along with the challenge of getting it working. (I'm now thinking that the cheap Rex unit, along with a suitable probe, might make a reasonable high-temp thermometer to use when melting scrap. No need to worry about switching anything, simply read the temp. Cheaper than buying a lead thermometer, too).

And that's one of the things I like about shooting black powder (besides the noise and smoke :grin:), it's been a great excuse to make all sorts of things.

It's called FUN!

el34
01-20-2014, 09:12 PM
You seem like a good guy and I sure hope you post about your project if/when you pull the trigger!
I'm still predicting the SSR will warm up nicely with that 15A current.

dikman
01-21-2014, 06:32 AM
Ummm, 15A? Where did you get that from? The pot only draws just under 4A, so a 25A SSR should barely get warm, I reckon.

I'm using a housing that was used for switching computer video monitors. It's only just big enough for the bits, according to my figuring, so should be nice and compact. I ripped out the innards and made a couple of aluminium panels for the front/rear (to cover the holes). The 230v outlet is fitted to the rear, along with a 230v power cord using a grommet clamp. I've decided not to cut out the PID hole until I actually have it (just in case!), then all I need to fit is a power switch and a grommet for the probe cable. Emails indicate that everything has been shipped, so should take about 2 weeks to get here.

As for being a "good guy", some might say that but I'm sure there are others who will disagree :wink:.

6bg6ga
01-21-2014, 07:05 AM
dikman,

I'm glad you liked my attempt at humor. I hope you got some useful information from this thread. Ebay is a good source of parts as we both know.

I learned something also... Frozone thru his PM to me has told me that I know exactly nothing about electronics and this is good information. Please disreguard all information that I have posted because Frozone says I'm incorrect. After learning this I will have no other recource but to give up my hobby of playing with valves and audio. I am also considering giving up my day job because I deal in electronics/audio/repair of large format audio systems. I am hoping that Frozone might like to school me thru this as I surely will need his experience the next time l open up one of say 15-20 racks of electronic equipment and look for the problem.

el34
01-21-2014, 01:20 PM
Ummm, 15A? Where did you get that from? The pot only draws just under 4A, so a 25A SSR should barely get warm, I reckon.


Yikes! My flu-infected brain crisscrossed your build with another post. That one has 3 heating elements, 5A each in parallel. Sorry about that!

dikman
01-22-2014, 07:21 AM
That's ok, el, you're obviously not taking enough drugs (for the flu, of course)[smilie=1:.

6bg, I think I see where your problem is - you should be using valves to build these things!:bigsmyl2:. Imagine what you could charge for a valve-powered, PID controlled temperature monitor. The hard-core, died-in-the-wool valve nuts would fall over themselves to get one - simply because it's got valves in it :grin:.

I'm only partly joking here - I worked with a (young) guy who is very good with electronics, but his real passion is valve amps. I discovered, through him, that there are people who are absolutely fanatical about valve-powered gear (guitarists, in particular, spring to mind. They have high regard for someone who understands the sound quality of such amps, and revere someone who can repair them too).

Keep them thar filaments glowing, pardner.

6bg6ga
01-22-2014, 07:30 AM
dikman

Please do keep us posted pictures and so forth on your PID project. If you want to go 1/2 valve let me know. I have some Mercury rectifiers and some tube regulators that will pretty up your project.

el34
01-22-2014, 03:38 PM
I was wondering if that's what he meant by valve.
In high school I kept myself emersed in the RCA Receiving Tube Manual.

The REAL el34 may stand now - - ->


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