Induction brass annealer redux

[Gina1]

Thanks but I did remove them for the picture. I used some kind of "thermal tape" but maybe I need a better conducting bond. I am going to add another SSR so it's a double pole like Gina recommended.

Personally I like the "clunk-thunkk" I get from the contactor DPST relay..

 

[Gina1]

Just out of curiosity, because of what normmatzen wrote, I took the top cover off the DPST contactor relay. It was in great shape. Very small amount of pitting. What you would expect under normal use. No arcing, no burned contacts. This could be because using a DPST relay opens both sides of the circuit at the same time. No place for possible flyback to go. Further if flyback is happening, the contacts on the contactor relay are far apart, arc could not jump it.

JMHO
Gina

 

[jthor]

I used that link to take a look at that solenoid. Unless the solenoid has a built in spring in the case, you may need to add a light weight spring to get the armature into the out position.
Take a look at the video in the beginning of this thread. You can see the spring on the solenoid.
Good luck
Gina

Thats what I plan on doing if it doesn't have an internal spring! Already bought everything else so I didn't want to buy anything else to make the 24v solenoid work.

 

[Gina1]

Thats what I plan on doing if it doesn't have an internal spring! Already bought everything else so I didn't want to buy anything else to make the 24v solenoid work.

Very good, glad to hear it.

 

[jthor]

Will be building my annealer with this computer case. https://www.amazon.com/dp/B00PDDMN6S/?tag=accuratescom-20
That's as soon as my parts from Jameco come in....

 

[Ferris 1977]

Hey guys,

thanks for all the infos you put out on this thread. I'm from Canada and been reading this with a lot of attention. I have all my parts on hand and I'm ready to build my first annealer. My electronic knowledge is really basic and I'm a little bit stressed. There is on thing that bugs me and can't quite understand the connections between the Varistor and the 30 amp 2 pole contactor. Can one of you brief me on this? pictures or dwgs?

Again thanks to all and can't wait to read more!!!

Phil

 

[Gina1]

Hey guys,

thanks for all the infos you put out on this thread. I'm from Canada and been reading this with a lot of attention. I have all my parts on hand and I'm ready to build my first annealer. My electronic knowledge is really basic and I'm a little bit stressed. There is on thing that bugs me and can't quite understand the connections between the Varistor and the 30 amp 2 pole contactor. Can one of you brief me on this? pictures or dwgs?

Again thanks to all and can't wait to read more!!!

Phil

Phil
The varistor goes across the actuator coil connections, on the relay. It's job is to dampen or short out the high voltage (CMF) (counter magnetic force). When power is removed from a relay, the collapsing magnetic field will induce a high voltage arc across the timer relay contacts, shorting them or wearing them out. The varistor removes this by conducting (shorting) this high voltage out. It does not conduct normal lower line voltage.
BTW just to be sure you have the right varistor, what is you line voltage. If it's 220 you will need a higher voltage varistor. The one in the parts list is for 110.
Hope this helps
Gina

 

[Ferris 1977]

Phil
The varistor goes across the actuator coil connections, on the relay. It's job is to dampen or short out the high voltage (CMF) (counter magnetic force). When power is removed from a relay, the collapsing magnetic field will induce a high voltage arc across the timer relay contacts, shorting them or wearing them out. The varistor removes this by conducting (shorting) this high voltage out. It does not conduct normal lower line voltage.
BTW just to be sure you have the right varistor, what is you line voltage. If it's 220 you will need a higher voltage varistor. The one in the parts list is for 110.
Hope this helps
Gina

Gina,

We do have 120v up here.

I did see differents config on these connection. From what I understand, one leg of the varistor goes to the positive on one side of the relay and the other leg goes to the negative on the other side of the relay...

Got it right.

Phil

 

[Gina1]

Gina,

We do have 120v up here.

I did see differents config on these connection. From what I understand, one leg of the varistor goes to the positive on one side of the relay and the other leg goes to the negative on the other side of the relay...

Got it right.

Phil

No.. It goes across the connections to the coil on the relay. To where your applying 110 volts from the timer to actuate the relay.

 

[jthor]

There’s a good picture of the varistor set up on page two.

 

[normmatzen]

Gina,

I stand by what I said about switching an inductive source OR load. If you find your contacts are in pristine shape, that means you are not switching an inductive load or source. Or, the load or source has been protected internally from fly-back.
It makes no difference (to a degree) how far the contacts are apart. The flyback arc will start soon as the contacts move just a tiny bit and once the arc is formed at small distances, it will sustain way past the breakdown in air for that spacing. No free lunch in physics!

 

[Gina1]

Norrmmatzen...

Yes, if we were dealing with just a straight single inductive coil. The CMF would cause the "flyback voltage. In the case for the inductor PCB, we are dealing with an oscillator circuit (load) not a straight inductor coil. What actually is happening on the contacts of the DPST relay I can't really say for sure, as it is encased and a closed case. Just checking the contacts, shows no sign of arcing.

 

[davexre]

I'm getting close... My first voltmeter/ammeter appears to not work. Or, I should say, it does work, but only when the 48v supply is shutting down and the voltage drops below about 15v - then the meter comes to life and follows the voltage down to about 8v, where it totally gives out. Which is interesting, because that means the meter is powering itself from the voltage supplied by the load, not it's own isolated supply... hmm. Not what I would have expected... ha ha.

I need to plumb my cooling system and set up my platform/trapdoor. Once I get all that working, I'll post pics of the whole build. My wood working is ... let's say primitive. At best. And parts of my wiring smell like a 3rd world prototype. Ha ha. But, so far, so good! The coil gets hot, the timer works correctly, etc.

 

[normmatzen]

I have as couple Royer oscillator boards in my garage and both of them as well as all literature on a Royer oscillator indicates a series inductor should be placed in series with the Dc voltage feed to the oscillator.
There will also be bypass capacitor from DC in to gnd to keep RF from going back into the power supply as well as snub the flyback from the choke out of the switch/relay connecting the DC supply to the Royer.

 

[Gina1]

I'm getting close... My first voltmeter/ammeter appears to not work. Or, I should say, it does work, but only when the 48v supply is shutting down and the voltage drops below about 15v - then the meter comes to life and follows the voltage down to about 8v, where it totally gives out. Which is interesting, because that means the meter is powering itself from the voltage supplied by the load, not it's own isolated supply... hmm. Not what I would have expected... ha ha.

I need to plumb my cooling system and set up my platform/trapdoor. Once I get all that working, I'll post pics of the whole build. My wood working is ... let's say primitive. At best. And parts of my wiring smell like a 3rd world prototype. Ha ha. But, so far, so good! The coil gets hot, the timer works correctly, etc.

Something strange there with your voltmeter. It should be running off the 12 volt DC supply. Check your wiring. It's been a while since I looked at the actual volt/amp meter, but I think it has a 2 wire connector, just to power the meter. Check that out. Sounds like you have the input power to the meter wired to the 48 volt PS.
Gina

 

[davexre]

Something strange there with your voltmeter. It should be running off the 12 volt DC supply. Check your wiring. It's been a while since I looked at the actual volt/amp meter, but I think it has a 2 wire connector, just to power the meter. Check that out. Sounds like you have the input power to the meter wired to the 48 volt PS.
Gina

I figured it out right before you posted... and that's a really good guess! The schematic on Amazon for this meter is a little vague. There are two harnesses included - one with two wires (red and black) and one with three (red, black, and yellow). I made an ASSumption that the two wire harness was power, and the three wire harness was the voltage and current sensor lines. That's like, logical, right? I'm not the only one who would think that way? LOL...

The schematic just shows lines coming off the central box, not necessarily with them grouped up in a clear way. It turns out, the two wire harness goes to the shunt - the red wire toward the load, and the black wire toward the negative terminal on the power supply. The three wire harness, the yellow goes to the positive side of the load, and red/black to isolated power (they recommend 5v for this one, but it will run on 12v just fine).

There's a part number on the unit that turns out to be used for another meter that looks exactly the same, but only does 0-10v. So, I thought maybe some had been mislabeled, and I got a 0-10v meter instead of 0-100v, and I was seeing the meter get unhappy about trying to measure a voltage greater than it was capable of. So, I wired it to my 5v supply to see if it would act better - and lo and behold, it just started working correctly. Then I caught a clue. ha!

Got my cooling system hooked up, now. That works like a champ after I diagnosed a single very slow leak (tightened a clamp more). Now for the trapdoor and platform, and current control on the power supply, and it'll be done!

 

[Jose_Luis_G]

I have as couple Royer oscillator boards in my garage and both of them as well as all literature on a Royer oscillator indicates a series inductor should be placed in series with the Dc voltage feed to the oscillator.
There will also be bypass capacitor from DC in to gnd to keep RF from going back into the power supply as well as snub the flyback from the choke out of the switch/relay connecting the DC supply to the Royer.

You are kindly requested to make a wiring diagram for your solution.
Please don't take everything as known and try to make it as clear as posible, including the right component names and features, so we all can implement your solution easily.
That should be a very nice help for many of us, which are not electronic experts.

 

[Gina1]

I figured it out right before you posted... and that's a really good guess! The schematic on Amazon for this meter is a little vague. There are two harnesses included - one with two wires (red and black) and one with three (red, black, and yellow). I made an ASSumption that the two wire harness was power, and the three wire harness was the voltage and current sensor lines. That's like, logical, right? I'm not the only one who would think that way? LOL...

The schematic just shows lines coming off the central box, not necessarily with them grouped up in a clear way. It turns out, the two wire harness goes to the shunt - the red wire toward the load, and the black wire toward the negative terminal on the power supply. The three wire harness, the yellow goes to the positive side of the load, and red/black to isolated power (they recommend 5v for this one, but it will run on 12v just fine).

There's a part number on the unit that turns out to be used for another meter that looks exactly the same, but only does 0-10v. So, I thought maybe some had been mislabeled, and I got a 0-10v meter instead of 0-100v, and I was seeing the meter get unhappy about trying to measure a voltage greater than it was capable of. So, I wired it to my 5v supply to see if it would act better - and lo and behold, it just started working correctly. Then I caught a clue. ha!

Got my cooling system hooked up, now. That works like a champ after I diagnosed a single very slow leak (tightened a clamp more). Now for the trapdoor and platform, and current control on the power supply, and it'll be done!

Glad to hear it. !! Your moving along. Takes time but it will be well worth it. "you built it" These annealers are being built all over the world... welcome to the club.

Gina

 

[normmatzen]

Attached is a schematic of a Mazzilli converter. This is simply a Royer Oscillator re-configured for MOS power transistors. Notice the inductor L1, this is included in all power oscillator boards. If the board has only 2 connections for the work coil, it will have two chokes (inductors) one supplying each side of the work coil. These chokes are usually on the order of 100 uHenries +/- a lot. Mine are toroid cores with the coils on them. Your board may or may not have a bypass capacitor connected from the left side of L1. If not, place a 0.1uF to 1 uF ceramic capacitor with a voltage rating at least twice your DC supply voltage. This capacitor is actually in parallel with the output capacitor of the DC supply when the contactor relay has the DC supply connected to the power osc. board. When the relay opens, a very high positive potential will instantaneously try to appear on the left side of L1! This is what can draw an arc across your relay. The addition of the capacitor will snub this high potential and protect your relay.

 

[Jose_Luis_G]

Attached is a schematic of a Mazzilli converter. This is simply a Royer Oscillator re-configured for MOS power transistors. Notice the inductor L1, this is included in all power oscillator boards. If the board has only 2 connections for the work coil, it will have two chokes (inductors) one supplying each side of the work coil. These chokes are usually on the order of 100 uHenries +/- a lot. Mine are toroid cores with the coils on them. Your board may or may not have a bypass capacitor connected from the left side of L1. If not, place a 0.1uF to 1 uF ceramic capacitor with a voltage rating at least twice your DC supply voltage. This capacitor is actually in parallel with the output capacitor of the DC supply when the contactor relay has the DC supply connected to the power osc. board. When the relay opens, a very high positive potential will instantaneously try to appear on the left side of L1! This is what can draw an arc across your relay. The addition of the capacitor will snub this high potential and protect your relay.View attachment 1034633

Thank you very much for the information you have supplied.

Unfortunately my skills seem to be out of order and I have not been able to understand a word of your explanation.

I'm afraid I need a fool-proof explanation which you cannot probably give.