Triggered by this thread : https://www.diyaudio.com/community/threads/compact-diy-friendly-dual-tps7a3301-power-supply.290858/ .
And the high prices and availability of low noise regulators. And problems with handeling smd parts.
I designed a realy quiet power supply with first a capacitor multiplier and then a TPS7A3301 regulator in TO220-7 housing(Cheap and throuhole).
Totalcost with transfomer,PCB and all parts about 20 euro.
I use two of them for dual rail suppy +/- 15V.
Schematic
View attachment 1096604
R1,Q1,C11 are part of the capacitor multiplier. With 200mA load the ripple before the TPS7A33 is only 5mV. With only 3300uf capactor it was 265mV.
After the TPS7A33 noise/ripple is lower then -120db, this is the limit of my measure equipment.
Transfomer
View attachment 1096552
TPS7A3301 TO220-7 housing.
Got the part for free, from the TI sample program.
View attachment 1096557
PCB
View attachment 1102185
PCB size is 50 x 100 mm. Ordered at JLCPCB for 8 euro(5 pcs).
Gerber files for ordering see below.
Ronny
And the high prices and availability of low noise regulators. And problems with handeling smd parts.
I designed a realy quiet power supply with first a capacitor multiplier and then a TPS7A3301 regulator in TO220-7 housing(Cheap and throuhole).
Totalcost with transfomer,PCB and all parts about 20 euro.
I use two of them for dual rail suppy +/- 15V.
Schematic
View attachment 1096604
R1,Q1,C11 are part of the capacitor multiplier. With 200mA load the ripple before the TPS7A33 is only 5mV. With only 3300uf capactor it was 265mV.
After the TPS7A33 noise/ripple is lower then -120db, this is the limit of my measure equipment.
Transfomer
View attachment 1096552
TPS7A3301 TO220-7 housing.
Got the part for free, from the TI sample program.
View attachment 1096557
PCB
View attachment 1102185
PCB size is 50 x 100 mm. Ordered at JLCPCB for 8 euro(5 pcs).
Gerber files for ordering see below.
Ronny
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Design is fine except that the output capacitor C15 is way too large - the datasheet recommends a 47uF X7R ceramic (ideal) although a film or very low ESR polymer would work.
Hal
Hal
The connected PCB has also big inputcapacitors 2200uf on the rails. I can try smaller capacitor but i can not measure it, because noise is lower then -120db. Load is not continu but change a lot(audio).
That does change things... I assumed you were making a bench power supply. In this case, you could save some money and go with a standard LM317 circuit (or LM337 if you are still wanting to regulate vie the negative rail) - the higher current limit might help with peak demands and will work fine for anything you are powering with it (given the 400mA limit given.)
Hal
Hal
Just updated schematic, PCB and gerber files. 47uf added as optimum minimum value at output.
LM317 has to much noise(max -105db), i still hear humm and noise in my 110db tweeters.
https://nl.aliexpress.com/item/1005...vid=202210041056383991947343938500006992864_1
LM317 has to much noise(max -105db), i still hear humm and noise in my 110db tweeters.
I did not know that, i have enough parts for my projects. They are still online(aliexpress) to buy.
https://nl.aliexpress.com/item/1005...vid=202210041056383991947343938500006992864_1
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If you do, it is most certainly not from an LM317 (especially after a CM filter) - and you are absolutely not hearing anything at -105dB.
Hal
Hal
I use this amp: https://www.diyaudio.com/community/...ny-recommendations.342387/page-4#post-7136313
Input is short to ground. Then i hear a little hiss and humm. When I ad tps7a47/33 regulator for U1(input opamp) everything is dead quiet.
Input is short to ground. Then i hear a little hiss and humm. When I ad tps7a47/33 regulator for U1(input opamp) everything is dead quiet.
For something like that the probable culprit is a ground loop or radiated noise aliasing into the circuit. Quick test is to take a large piece of aluminum foil and cover various parts of the circuit and see if it has any effect. It won't be thick enough to to block low frequency or magnetic interferance, but it can help eliminate some RF issues. A huge source of radiated noise is LED or fluorescent lighting so see if turning the lights out helps. Also an AP close by can cause problems. But still, I would think that the most likely problem is with a ground or a problem with your existing power supply. What you had originally planned was a good idea - it just did nor require that high a performance part.
Hal
Hal
Somebody has to do it:
- Distance between diode bridge, transformer and filter caps is small. Please measure temperatures at specified maximum load.
- Through hole may seem to be a design feature but it does not make things easier in a dominantly SMD world.
- Clearance between metallized mounting holes and 230V mains voltage carrying PCB track at the fuse holder is absolutely below required clearance. Please change to normal clearance. Many will use metal standoffs as standard with PSU boards and onboard transformer.
Not wanting to be overly criticizing but please note that you publish stuff on a public DIY website with people copying stuff or having PCBs made. It should be 100% safe. Only add gimmicks and publish when stuff has been reviewed and tested by another person.
- Distance between diode bridge, transformer and filter caps is small. Please measure temperatures at specified maximum load.
- Through hole may seem to be a design feature but it does not make things easier in a dominantly SMD world.
- Clearance between metallized mounting holes and 230V mains voltage carrying PCB track at the fuse holder is absolutely below required clearance. Please change to normal clearance. Many will use metal standoffs as standard with PSU boards and onboard transformer.
Not wanting to be overly criticizing but please note that you publish stuff on a public DIY website with people copying stuff or having PCBs made. It should be 100% safe. Only add gimmicks and publish when stuff has been reviewed and tested by another person.
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