I have already a +-24v power supply for FW amps and want to use this as +-16v power source for other amp too.
Is there any easy way except changing transformer?
Is there any easy way except changing transformer?
No.
SLB is not a voltage regulator.
The transformer voltage and load determines output voltage.
SLB is not a voltage regulator.
The transformer voltage and load determines output voltage.
Not easily. You need a different transformer. SLB is not same as a regulated PSU that burns off voltage via a pass transistor. It is a ripple reducer and max voltage drop is 3 to 4v.
To drop 10v, you could string a bunch of diode bridges (heatsinked type) and get 0.6v per diode. 10/0.6= 17 diodes. Each full wave bridge is 2 stages so 8 of them in series could work. You will burn off a lot of heat. Easier to get a new trafo or if you are brave, unwind it number of turns to get the voltage you need.
To drop 10v, you could string a bunch of diode bridges (heatsinked type) and get 0.6v per diode. 10/0.6= 17 diodes. Each full wave bridge is 2 stages so 8 of them in series could work. You will burn off a lot of heat. Easier to get a new trafo or if you are brave, unwind it number of turns to get the voltage you need.
That’s a good idea but that has to make a lot of heat if there is any appreciable current. I often use the Easy Peasy cap Mx (also MOSFET) to drop 4 volts and have -50dB ripple reduction.
https://www.diyaudio.com/community/threads/jumas-easy-peasy-capacitance-multiplier.297921/
https://www.diyaudio.com/community/threads/jumas-easy-peasy-capacitance-multiplier.297921/
Hi X, any idea when the dual rail SLB pcb's will be back in stock in your Etsy store. You mentioned this above on the 22nd September - so I thought they would be available by now 2 months later.
Sorry I didn’t get around to ordering them yet. I have been dealing with some key project milestone reviews for the day job and was really busy. I will place an order and should have them in a few weeks. You are welcome to get them from Mikerodrig27 if you cannot wait.
Hi again X, I will get the 2 pcb's from Mike, can you tell me if there are any differences from the original dual rail SLB as shown in post #135 of May 2019 and the version 1.2 dated Feb 2020 which Mike has got?
If so, can you point me to the relevant changes thanks again.
If so, can you point me to the relevant changes thanks again.
The only thing that might be different is the Molex connector for the off board BJTs. They were 90deg, the. 0deg (vertical), then back to 90deg.
If the board looks like this:
It’s the main one I have been selling for the last 3 years. It is the 90deg(horizontal) jack. Other than that nothing changed.
If the board looks like this:
It’s the main one I have been selling for the last 3 years. It is the 90deg(horizontal) jack. Other than that nothing changed.
@gary s
When you install RV2, flip it around. Note if installed as the silkscreen suggests, access to RV2 will be difficult with the heatsink size recommended in the BOM. Some have also used smaller heatsinks for HS1, HS2 but I personally haven’t measured how hot the BD139/140 transistors get under load. Smaller heatsinks there will also solve the problem of RV2 access.
RV1 and RV2 make small changes in the output voltage. Ideally, one should view the ripple voltage (peak to peak) on a scope while UNDER load and adjust RV1, RV2 for lowest ripple.
I think if X does another revision of these boards, he can eliminate RV1,RV2 as the differences in ripple appear to be pretty small; in other words the capacitance multiplier circuit itself drops ripple quite tremendously compared to the usual CRC supplies. All measurement info is in the 1st ten pages of this thread. Remember the amount of ripple you get is linearly related to the amount of current being drawn by the load. The worst load are very high bias Class A (particularly single ended ones for 4 ohm loads) - since they have a high constant bias (think 2, 3, 4 amps) and that’s where capacitance multiplier power supplies can shine.
Best,
Anand.
When you install RV2, flip it around. Note if installed as the silkscreen suggests, access to RV2 will be difficult with the heatsink size recommended in the BOM. Some have also used smaller heatsinks for HS1, HS2 but I personally haven’t measured how hot the BD139/140 transistors get under load. Smaller heatsinks there will also solve the problem of RV2 access.
RV1 and RV2 make small changes in the output voltage. Ideally, one should view the ripple voltage (peak to peak) on a scope while UNDER load and adjust RV1, RV2 for lowest ripple.
I think if X does another revision of these boards, he can eliminate RV1,RV2 as the differences in ripple appear to be pretty small; in other words the capacitance multiplier circuit itself drops ripple quite tremendously compared to the usual CRC supplies. All measurement info is in the 1st ten pages of this thread. Remember the amount of ripple you get is linearly related to the amount of current being drawn by the load. The worst load are very high bias Class A (particularly single ended ones for 4 ohm loads) - since they have a high constant bias (think 2, 3, 4 amps) and that’s where capacitance multiplier power supplies can shine.
Best,
Anand.
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