Sjöström Audio DIY forum

With a 100 ohm resistor, I get a 0.9V difference on Q2 (pins 2 and 3), and a 1.67V difference on IC1 (LM317, pins 2 and 3). Thanks again.

I'll suggest that you take three 1N4148 in series instead or put the led in a shrink tube or paint it black. If you increase the H1 voltage, then the drop out voltage will increase and then you'll need to adjust the voltage of the IC1.

When you load with 100 ohm, what is the voltage between emitter and collector of Q2? Voltage between in and out of IC1?

I've taken some measurements and with a 100 Ohm resistor, the voltage drops from 12.3V to 5.2. With a 1k resistor, then there is no drop.

I'll suggest that you try with 120 ohm or something. This would create 100 mA.

If the regulator works you should have a voltage drop of a few millivolts only and the voltage at pin 2 and 3 on the opamp should be within 1-2 mV, and that is 6.25V if the output voltage is 12.5 V.

Well, I don't know how much current can I draw before voltage drops. What would be the best way to actually measure this (variable CCS, resistor, ... )?. Thanks.

How much current are you able to take out before you'll get a voltage drop?

I'll recommend that you connect to the unregulated voltage in order to avoid unnecessary heat in the voltage regulator. Adjust the resistor value so the light is enough.

Per Anders,

I have installed a +12V SSR01 regulator to power up a DDDAC board. At no load, the regulator provides 12.3V but when the DAC board is connected, the output voltage from the regulator drops to 2.5V.

I was wondering if other users have already faced this issue, and how to solve it. Thanks for any input you could provide!

Operation conditions are as follows:
On the SSR01 board, both J1 and J2 are bridged.
The DAC board should be drawing around 100mA.
Input voltage is 30VDC
There is a large heatsink over the LM317
Upfront DC regulation is done with a LC circuit (diode bridge, 17H in series, 100uF polypro in parallel)

Hi,

I'm building a 7V SSR01 using a 9V AC supply, which when rectified and accounting for losses should give nearly 12V output, which should be ok with the SSR01 with AD825 I hope.
The PCB will be partly visible through a perforated cardboard inside an old tube radio, and would like avoid any shining LEDs if possible.

Would it thus be possible just to use a 2.4V zener diode instead of H1, and just leave R3 at 2.2k? Or is the base current of the BC556B negatively affected by this (as I-V characteristics of zeners and LEDs are not the same)
Or would it be possible to even use a 3.3V zener like used as DZ1, possibly lowering the value of R3?