So with 4 x 2.1 and 10R, I get ~150mA headroom and with 3.9, ~500mA. 200mA (2x load) needs 8.6R. I assume I can choose any intermediate values to suit my desire/heatsink.
Feeding your numbers into the spreadsheet (4 green LEDs @2.1V in the CCS) I get R101 of 8R6? With your Vin and Vout you'll be producing a lot of heat in Q101 and a lower Vin might be better.
I agree, but I have a great source of 25VDC from a battery bank that avoids all the issues of AC/DC conversion and provides a very quiet input, so it makes it worthwhile.
Is there an advantage to using all 4 LED's? Using 3 Reds results in a R <1W whereas using 4 x Green requires an R ~5W. What is the down side of using fewer/lower Vf LED's?
From the bib manual:
"In the newer batch of SSLV1.1 boards, 4 LED positions are available for ease in higher current settings. They can either be used for 3 LEDS and one of them be a wire jumper, or be fully populated if your current demands push VGS and your resistors stock fits higher values. Excess voltage across R101 when there is enough to set the CCS with fewer LEDS, only creates excess dissipation, gives no advantages."
"In the newer batch of SSLV1.1 boards, 4 LED positions are available for ease in higher current settings. They can either be used for 3 LEDS and one of them be a wire jumper, or be fully populated if your current demands push VGS and your resistors stock fits higher values. Excess voltage across R101 when there is enough to set the CCS with fewer LEDS, only creates excess dissipation, gives no advantages."
Can you give me a link to that manual? I think I must have an older one.
Thanks
A question from a newbie. I have constructed both the positive and negative regulators. They have been built to power a BA-3 preamp once the DIY store has the boards back in stock. Thought I would get a head start.
I am using a 12R in the R101 position on the V+ regulator giving me about 116ma. Using the same 12R in the R201 position on the V- regulator I have only about 81ma.
So do I need to have matching (or close) current in both the V+ and V-? Not sure how this would affect the BA-3. I would assume the differences in components resulted in differences in the current. I did try a 7R in the R201 position and have 119ma.
Thanks for any insights.
David
I am using a 12R in the R101 position on the V+ regulator giving me about 116ma. Using the same 12R in the R201 position on the V- regulator I have only about 81ma.
So do I need to have matching (or close) current in both the V+ and V-? Not sure how this would affect the BA-3. I would assume the differences in components resulted in differences in the current. I did try a 7R in the R201 position and have 119ma.
Thanks for any insights.
David
NMOSFET and PMOSFET non matched devices show Vgs differences. That is the cause. Keep the 7R R201 since it equalizes the available currents between polarities. Changing the set resistor value is the easiest way to centrally deal with the rest of tolerances.
Its nice to know that your polarities have the same current potency. Not sure if BA3 would notice, but anyway. Only make sure that the BA3's peak current consumption per rail when tested with a full swing sinewave is half what the regs can give on each rail. So to have good dynamic headroom. In general its not uncommon to find enough users allowing 200-350mA CCS to each reg, even for 50mA max load demand, just to go hot-rod.
Its nice to know that your polarities have the same current potency. Not sure if BA3 would notice, but anyway. Only make sure that the BA3's peak current consumption per rail when tested with a full swing sinewave is half what the regs can give on each rail. So to have good dynamic headroom. In general its not uncommon to find enough users allowing 200-350mA CCS to each reg, even for 50mA max load demand, just to go hot-rod.
