The big TEC driver thread!

[dnar]

Personally I feel moving heat from LD to base plate is fairly insignificant considering the thermal mass of the base plate and the other heat sources sink'd to the plate from drivers and power supplies.

At least fan cooling on the electronics side can work at removing this heat from the case.

I have been dreaming of a cooling tunnel using the heatsinks below to remove heat from the case. One could in theory mount galvo drivers, LD drivers and SMPSU directly to this heat sink tunnel.

http://jaycar.com.au/productView.asp...T&SUBCATID=751

http://au.element14.com/fischer-elek...12v/dp/1222507

Just dreaming of a case with no dust issues at all.

[Solarfire]

Looking good!

If you want to reduce part count, R16 is not necessary as the MCU outputs sink when low.

R12 appears pretty low considering the other LED's with 1k5 on 5V.

The Omron relay consumes 30mA and the relay is wired to be activated in normal use (as I would prefer). Why not change to the G1V-1 12 to lighten the regulator load? if you do this, route the GND NET at T1's emitter directly to X3-2.

Can you tweak the NTC amplifier to provide exactly 50ADC/C?

If you want another challenge, use the spare op-amp to provide a 100mV/C test output.

Looking good mate.

Revised Schematic..

Dimensioned inductor to 33uH/0R084/100kHz, asuming the Attiny24 can do 100kHz or better PWM.

Fixed one schematic error

[dnar]

Revised Schematic..

Tick. Stamp. I think we have nailed it.

[LaNeK779]

Is there any chance that anybody will be making a pcb for this?

maybe they want to make a couple more and split the development / fixed costs?

just asking...

[Solarfire]

Is there any chance that anybody will be making a pcb for this?

maybe they want to make a couple more and split the development / fixed costs?

just asking...

I'm on it at this moment

[dnar]

I'm on it at this moment

Cool. I'll get the code rolling if you like.

[Solarfire]

Cool. I'll get the code rolling if you like.

Sounds good to me. I'm gooing to get 4 boards done up for testing for now. That will take about 10 days. If you mail me your adress I'll get 2 of those to you.

I got the placment/routs done yesterday but before I send it off for manuufacturing, I want to do another simulation on the inductor, currently assuming >=100kHz PWM @ 50% with an Inductor of 33uH/0R084/3.5A which is giving 10% ripple at 4.6A which should be significantly less @ <= 3A. Got any objections on that one?

Will a copper pour ground plane be sufficient shielding for the Tiny24?

[dnar]

Sounds good to me. I'm gooing to get 4 boards done up for testing for now. That will take about 10 days. If you mail me your adress I'll get 2 of those to you.

I got the placment/routs done yesterday but before I send it off for manuufacturing, I want to do another simulation on the inductor, currently assuming >=100kHz PWM @ 50% with an Inductor of 33uH/0R084/3.5A which is giving 10% ripple at 4.6A which should be significantly less @ <= 3A. Got any objections on that one?

Will a copper pour ground plane be sufficient shielding for the Tiny24?

All good with the inductor/frequency.

A poly pour will be fine, just ensure the heavy ground currents (TEC and relay) are not part of the tiny/opamp/regulator ground path, and tie the current sense resistor to tiny ground, not the h-bridge.

[FourDee]

I have a remark about the relay used.
I see you're using a SPDT relay for switching the color signal.

ILDA standard specifies the color signal to be differential so IMHO a DPDT relay should be used.
The two outgoing wires could be connected together when inhibited

[Solarfire]

I have a remark about the relay used.
I see you're using a SPDT relay for switching the color signal.

ILDA standard specifies the color signal to be differential so IMHO a DPDT relay should be used.
The two outgoing wires could be connected together when inhibited

I don’t know, I may be missing something here but the relay is either switching thru the modulation signal (for example pin 5 of the DB25 Ilda conector 0-5V + [red]) or open circuiting ilda side and putting 0V(gnd) on the modulation in of the LD Driver which should blank lasing? Right?