Induction brass annealer redux

[bertn]

Hello all,

Still waiting for my induction board to arrive....
So I ordered the same board as listed in post 1 and it is supposed to run on 12-48vdc.

I was wondering what the minimum amount off watts (V x Amp) is that's needed to
run the annealer.

Trying to build it as economical as possible I salvaged two 12vdc power supplies from free scrap pc's
and have them currently connected in series to give me 24v.
The one is rated for 350w@12vdc and the other 400w@12vdc.
From what I have been reading online is that in this configuration I can only get 350w@24vdc out of it.
Is that correct and would that be sufficient?

Please share your experiences.

Thanks,
Bert

 

[Jose_Luis_G]

Hello all,

Still waiting for my induction board to arrive....
So I ordered the same board as listed in post 1 and it is supposed to run on 12-48vdc.

I was wondering what the minimum amount off watts (V x Amp) is that's needed to
run the annealer.

Trying to build it as economical as possible I salvaged two 12vdc power supplies from free scrap pc's
and have them currently connected in series to give me 24v.
The one is rated for 350w@12vdc and the other 400w@12vdc.
From what I have been reading online is that in this configuration I can only get 350w@24vdc out of it.
Is that correct and would that be sufficient?

Please share your experiences.

Thanks,
Bert

In my opinion it is a bit short. Think of working in a 600W basis, much better if it is 750W.
Anything below 600W will give you a lot of headaches.

 

[Gina1]

Hello all,

Still waiting for my induction board to arrive....
So I ordered the same board as listed in post 1 and it is supposed to run on 12-48vdc.

I was wondering what the minimum amount off watts (V x Amp) is that's needed to
run the annealer.

Trying to build it as economical as possible I salvaged two 12vdc power supplies from free scrap pc's
and have them currently connected in series to give me 24v.
The one is rated for 350w@12vdc and the other 400w@12vdc.
From what I have been reading online is that in this configuration I can only get 350w@24vdc out of it.
Is that correct and would that be sufficient?

Please share your experiences.

Thanks,
Bert

Hi bert...

Good way to put it in your question. "share your experiences"
Things we can't change (1) the induction PCB (2) the size of the coil [if you built it to the spec's]
Things you can change (1) how far in the coil you insert the case (2) how long you anneal, time wise.

Here's my experience. with this coil design (which works very well for 308, 6XC, 6mm dasher, 300 win mag, etc The annealer works best if the neck and shoulder are in the coil. if they are and the power supply is around 48 volts (mine is set to 43.5 volts), and I will pull 12-12.5 amps and annealing time is about 5.1 seconds. This is with a 600 watt power supply. Because it is a 48 volt PS the max amount of current I can pull is 12.5 amps.
If your going to use a lower voltage power supply, you have to figure what the max amount of current you can pull. At 24 volts, the max current is about 14.6 amps (350 watts)(power = voltage X current) Lower power also means lower energy, so annealing time will take longer.
The quick procedure is to have the annealer running, while watching your ammeter. You will see a reading with no case in the coil. As you insert the case in the coil, the current reading will rise.
With your set up, with you power supply the max reading you want to see is 14.6 amps. (14.0 to be safe). Once you have determined the case position for max current, then you play with annealing time.
Taking a case painted with Tempilaq, temperature indicating fluid (750 degree) Start playing with your annealing times, until you see color changes where you want them. I my case 1/4" below the shoulder.

At this point I have not heard from anyone building that is using a lower volt/current power supply. One fellow was going to use a 36 volt PS, but has not gotten back to me.

Hope this helps
Gina

 

[bertn]

In my opinion it is a bit short. Think of working in a 600W basis, much better if it is 750W.
Anything below 600W will give you a lot of headaches.

What kind of headaches, besides the annealing taking longer?
How do you know or what have you tried?

 

[Jose_Luis_G]

What kind of headaches, besides the annealing taking longer?
How do you know or what have you tried?

I have a 500W power supply and it has a built-in self-protection, so when I go above 10A it shuts off.
My needs for a proper annealing are in the range of 9.5A for that power supply, and the annealing time goes to 7 sec and above. This makes the cooling water to get hot very often and both things, time of annealing and change of cooling water, take you to a larger time of operation <> lower production.
Don't forget that the coil itself without load drags 6.7A at 47.7V (in my case), which is about 320W.

 

[kit-808]

just be careful of small watt pc power supply's as they are not very high amps. also make sure that its rates on the 12v line, as some are are split across all the power output 3,5,12v. or you could fry both of them

 

[normmatzen]

Bert,

To answer your question completely and without adding "little red wheels" to the subject;

If you have two 12 V supplies and you want to hook them in series.
1. you actually have one supply (the 350 Watt unit) that will put out 29Amps. ( 350 divided by 12 Volts) and one that will put out 33 Amps
(the 400 Watt unit). If you put them in series, they will both run at the same current. That means that when the 350 Watt unit gets to 29 Amps, it will be current limited at that current so the combination can only supply 29 Amps which will be limited by the 350 Watt supply. With 29 Amps available, you have 29 Amps times 24 Volts for a total available power of 696 Watts.

Of course, one of the supplies will have its ground pin at +12 Volts and its +12Volt pin at 24 Volts so you must be sure the output can be allowed to "float" above the AC ground by 12 Volts. Or, the two outputs can work with a 12 Volt common mode voltage.

 

[Gina1]

Bert,

To answer your question completely and without adding "little red wheels" to the subject;

If you have two 12 V supplies and you want to hook them in series.
1. you actually have one supply (the 350 Watt unit) that will put out 29Amps. ( 350 divided by 12 Volts) and one that will put out 33 Amps
(the 400 Watt unit). If you put them in series, they will both run at the same current. That means that when the 350 Watt unit gets to 29 Amps, it will be current limited at that current so the combination can only supply 29 Amps which will be limited by the 350 Watt supply. With 29 Amps available, you have 29 Amps times 24 Volts for a total available power of 696 Watts.

Of course, one of the supplies will have its ground pin at +12 Volts and its +12Volt pin at 24 Volts so you must be sure the output can be allowed to "float" above the AC ground by 12 Volts. Or, the two outputs can work with a 12 Volt common mode voltage.

Ahhhh, adding in the little red wheels. My gut feel is the power supplies were not designed to carry that much current, ether the wires coming out of the power supplies or the land prints on the power supply circuit boards. Somewhere along the lime there is a going to be a sufficient voltage drop when you pull that much current going to the inductor PCB.
But what do I know... It may work. Go ahead and try it, and let us know it it works. This is every bodies build.
Good luck
Gina

 

[normmatzen]

I guess I had better define what "little red wheels" means!

When I was VERY young and going through the Navy Aviation
Electronic Technician "A" school, we had a test every Friday. These tests alternated week to week with a "sweat test" one week and a "non-sweat test" the next. The sweat test counted toward your course grade. The instructors would always prepare us for the test by reminding us to put our names on the paper first! Then they would remind us to ignore the "little red wheels." That was the information on the questions that had no relevance at all, just confused us. Just as the color of a wheel on a vehicle was not relevant to any operating function on the vehicle!
It was also to prepare us for actually troubleshooting faulty equipment where often we would find a "fault" that had no relevance to the proper operation of the gear.

And, if a power supply is specified for a given power output, the expectation is it will reliably supply that power right up to the limit. What is more relevant tho in this case, the output voltage must be high enough but not higher than the oscillator board is designed for. And, the output current must be high enough to satisfy the current demand of the oscillator. For example, the oscillator may use up to 15 amps, so one may select a supply rated at 20 amps for margin while supplying, say, 24 volts. But, if the oscillator has an inrush current due to filter capacitors or both transistors may start out "on" and quickly one will shut down, then there may be a start up surge of 25 amps. In that case, the supply will limit at 20 Amps and the voltage will sag down till 20 Amps is flowing. The resulting output could sag down so low that the oscillator will never start!
When a power supply is rated at a given power, that usually refers to not only the product of Voltage and Current the supply will supply, but it is an indication of the power the unit is designed to dissapate!
As an example, if the supply is rated at 300 watts and 24 Volts out, that implies a max current of 12.5 Amps. If the supply has an adjustable output Voltage, with 5 Volts set, the maximum current is still 12.5 Amps as that was what the supply was rated at. Even though the supply is now delivering only 62.5 Watts, it is still dissipating 300 Watts as the difference from 24V to 5 V or 19 V, is now across the pass element and heating up the unit at the 300 Watt rate.

 

[Gina1]

I guess I had better define what "little red wheels" means!

When I was VERY young and going through the Navy Aviation
Electronic Technician "A" school, we had a test every Friday. These tests alternated week to week with a "sweat test" one week and a "non-sweat test" the next. The sweat test counted toward your course grade. The instructors would always prepare us for the test by reminding us to put our names on the paper first! Then they would remind us to ignore the "little red wheels." That was the information on the questions that had no relevance at all, just confused us. Just as the color of a wheel on a vehicle was not relevant to any operating function on the vehicle!
It was also to prepare us for actually troubleshooting faulty equipment where often we would find a "fault" that had no relevance to the proper operation of the gear.

And, if a power supply is specified for a given power output, the expectation is it will reliably supply that power right up to the limit. What is more relevant tho in this case, the output voltage must be high enough but not higher than the oscillator board is designed for. And, the output current must be high enough to satisfy the current demand of the oscillator. For example, the oscillator may use up to 15 amps, so one may select a supply rated at 20 amps for margin while supplying, say, 24 volts. But, if the oscillator has an inrush current due to filter capacitors or both transistors may start out "on" and quickly one will shut down, then there may be a start up surge of 25 amps. In that case, the supply will limit at 20 Amps and the voltage will sag down till 20 Amps is flowing. The resulting output could sag down so low that the oscillator will never start!
When a power supply is rated at a given power, that usually refers to not only the product of Voltage and Current the supply will supply, but it is an indication of the power the unit is designed to dissapate!
As an example, if the supply is rated at 300 watts and 24 Volts out, that implies a max current of 12.5 Amps. If the supply has an adjustable output Voltage, with 5 Volts set, the maximum current is still 12.5 Amps as that was what the supply was rated at. Even though the supply is now delivering only 62.5 Watts, it is still dissipating 300 Watts as the difference from 24V to 5 V or 19 V, is now across the pass element and heating up the unit at the 300 Watt rate.

Thanks for the explanation on the little red wheels.

Oh, and you are correct. Double the voltage (24 volts) but limited to the current of the low current PS. So the wattage does increase P=E X I
As I said give it a try. It's a way to limit the cost of the build. And that's a good thing.

 

[Terry Altom]

Ahhhh, adding in the little red wheels. My gut feel is the power supplies were not designed to carry that much current, ether the wires coming out of the power supplies or the land prints on the power supply circuit boards. Somewhere along the lime there is a going to be a sufficient voltage drop when you pull that much current going to the inductor PCB.
But what do I know... It may work. Go ahead and try it, and let us know it it works. This is every bodies build.
Good luck
Gina

I fully agree. PC power supplies simply are not engineered and built to produce the kind of amperage for that period of time.

 

[GrocMax]

Sub board done.

Left edge 5v 1A regulator

Top row connectors L-R-
Optical start switch output to timer.
Optical stop switch output to timer
Fan control NTC thermistor #1 (soldered to radiator tank)
Fan control NTC thermistor #2 (bolted to induction board)

2nd row L-R
Optical (interruptive) start switch LED and phototransistor
Optical (reflective) stop switch

3rd row L-R

12v/0v in
Current trimmer pot for PS, 2.5v-5.0v 50% to 100% of rated current
Voltage trimmer pot for PS, 2.5v-5.0v 50% to 100% of rated voltage

Bottom row L-R

Trimmer voltages to PS for PS remote control of current and voltage
Fan #1 (12v PWM, radiator)
Fan #2 (12v PWM, induction board)

The tiny green DIP to TDFN adapter boards are the fan controller IC's,
MAX31740. Round trimmer pots (10K) set minimum DC%, square ones (200K) set temp span from min DC%-100%. Those TDFN chips are 2mm on the side with 0.5mm pitch pads and a challenge to solder.

 

[Gina1]

Sub board done.

Left edge 5v 1A regulator

Top row connectors L-R-
Optical start switch output to timer.
Optical stop switch output to timer
Fan control NTC thermistor #1 (soldered to radiator tank)
Fan control NTC thermistor #2 (bolted to induction board)

2nd row L-R
Optical (interruptive) start switch LED and phototransistor
Optical (reflective) stop switch

3rd row L-R

12v/0v in
Current trimmer pot for PS, 2.5v-5.0v 50% to 100% of rated current
Voltage trimmer pot for PS, 2.5v-5.0v 50% to 100% of rated voltage

Bottom row L-R

Trimmer voltages to PS for PS remote control of current and voltage
Fan #1 (12v PWM, radiator)
Fan #2 (12v PWM, induction board)

The tiny green DIP to TDFN adapter boards are the fan controller IC's,
MAX31740. Round trimmer pots (10K) set minimum DC%, square ones (200K) set temp span from min DC%-100%. Those TDFN chips are 2mm on the side with 0.5mm pitch pads and a challenge to solder.

OK------- I think I would understand better what you are doing, if I could see a schematic. Curious I am
Gina

 

[GrocMax]

OK------- I think I would understand better what you are doing, if I could see a schematic. Curious I am
Gina

I'll get a full dwg done eventually but the reason for the sub board was because I wanted to 'fancy it up' a bit.

The 48V 750w PS I bought has a remote current and voltage adjustment capability but requires an external 2v minimum to 5.5v max signal source. The reflective optical switch requires a 5v power source, and I found this neat little simple fan control IC that also can use a 5v. So a 5v regulator and a small board became necessary.

Soldering that tiny chip onto a DIP adapter board is a challenge. Destroyed a couple trying to hot air reflow, recommend a 10w-20w iron with a TINY tip and a 5x or better loupe/magnifyer. Adapter boards are Schmartboard 204-0021-01.

Two 10K pots with a 10K resistor to gnd provide the external 2.5v to 5v signal that allows current and voltage adjustment of the PS on the fly from 50% to 100% rating. With 5.5v it becomes 110% but I saw no need to push it so 100% max it is.

The optical switches are for timer start and timer stop signals. Both the LED's use up a max of 200mW of 5v power, one requires a 39 ohm 1 watt 5v (or 120 ohm 12v) power resistor the other does not need a resistor its internal. 2n4401 transistors and 1K and 10K pullups are involved inverting the signals so the timer can deal with them.

The fan controller I found searching for other stuff, I though it was a neat deal, really simple. Maxim Integrated 31740 http://www.mouser.com/ds/2/256/MAX31740-253424.pdf

It is for use on 3 and 4 wire PWM controlled fans, the IC does not power up or gnd the fan, just outputs the low level PWM square wave signal the fan needs for its own speed control, no output transistor needed for a PWM controlled fan, use an output transistor on a 2 wire fan. You set PWM frequency with an external timing capacitor, in this case 25K Hz (430pF), use virtually any NTC thermistor (5K to 10K @ 25c is ideal) I chose an Epcos 5K @ 25c ring terminal unit B57703M0103A017 one will be soldered to radiator exit tank, other bolted to a heatsink, now have closed loop cooling control fans run when they need to at the speed they need to.

The pullup resistor (or pot) to 5v for the NTC determines fan 'start' temp, for simplicity I chose a 4.7K resistor which sets the start temp at about 27-28c with a 5K NTC.

The duty cycle minimum can be set to zero or whatever you wish by a voltage signal, in this case a 5v pullup thru a 27K resistor to center wiper of a 10K single turn pot allows 0v to ~1.66v at the Dmin pin which is 0 to ~50% DC for the minimum DC%. Not all fans work the same at lower DC% having this adjustment range helps.


The temp span from minimum DC% to 100% fan speed is set by a single resistor or multiturn pot, depending on your NTC thermistor and desired control range. A 100K pot would cover all the range you'd need with a 5K or 10K NTC.

So the fans idle at 30% or so DC% until 28c then increase speed with temp to 100% at 75c or whatever you wish. A high RPM PWM fan can really push a lot of air (60+ CFM) thru a radiator at full speed.

 

[itchyTF]

I like the "professional" look so I did this board. Uses a PIC micro (not installed) to decode a 3 wafer thumb/push wheel for setting time (10ms resolution), monitors up to 2 optical sensors (I only use 1) and can control 3 solenoids (only using 1). Also controls on/off, lockout for changing time and some LEDs.

 

[GrocMax]

I'm jealous. Call me old and analog

 

[Gina1]

My hat's off to you all.... WOW

Gina

 

[jkl]

I'll be first to say, I'll take one!! Now that's out of the way.
John

 

[itchyTF]

I'm jealous. Call me old and analog

Don't know how "old" you are but I turned 70 last month ( or , not sure). I'm mostly analog but I dabble in digital.

 

[itchyTF]

I'll be first to say, I'll take one!! Now that's out of the way.
John

Actually the one in the picture is an extra. Any takers? Only costs $1,000!!