Effectively this is using two halfwave rectifiers one for positive one for negative. This means each polarity isgetting supplied with intermitent pulses of power. Even with the complex input filters pulsating dc will arrive at the regulators. This maybe ok for non critical low current applications, but for things like quality audio a tranformer with two secondaries and fullwave rectification is needed.
@MyVanitar
2 жыл бұрын
My claim also confirms your comment. for high current applications, even a full wave rectifier is not enough and we need stronger filtering methods, in future, I will cover that
@AdamTheAd-vanc3d
Жыл бұрын
One thing I dont remember hearing being mentioned is fusing at the transformer side. Can anyone elaborate please.
@SebastianScholle
3 жыл бұрын
Nice way to get also negative voltage! But with this design you need that extra filtering caps, which you have. Good job.
@MyVanitar
3 жыл бұрын
This is one of the easiest and cheapest methods
@FileFixer007
4 жыл бұрын
Adding 10μF bypass capacitor from ADJ pin to GND can improve PSRR for additional -7dB.
@MyVanitar
4 жыл бұрын
Thanks
@FileFixer007
4 жыл бұрын
@@MyVanitar You can see in LM317/LM337 datasheet that manufacturer recommended to to add bypass capacitor between ADJ and GND pins for lowering PSSR about -7dB but with good relationship between bypass capacitor and output filter capacitor it is possible to lower much more PSSR then just add that 10μF between ADJ nd GND pins. TNT audio measure and experimeted with this relationship and conclude that is very good PSSR rejection and relationship between that two capacitors are 22μF on bypass and 220μF at output filtering capacitors (C9/C10 on your scheme). Result is additional --20dB reduced PSSR and now is under -80dB at final measurements. In case if you add bypass capacitor than you need to reconnect diodes D5/D6 directly from ADJ to OUT pins on LM317/LM337 because now that diode have this line cuted with bypass capacitor and now does not have direct connection between that pins (see LM317/LM337 datasheet). I like your schematics because does not need dual transformer output and it is simple to add another power supply in parallel with different voltage eg. 5V in parallel with same transformer. In that case we can have +/-12V and another +5V dual power supply for many different aplications eg. FY6800/6900 function generator need better power supply instead of junk inside them and I see that your scheme have realy nice perspective for that. Many thanks for your great scheme.
@MyVanitar
4 жыл бұрын
@@FileFixer007 Thank you very much for the information. Yes this circuit is useful in many double supply scenarios, where each supply rail can be adjusted individually.
@frontier9
3 жыл бұрын
Cool but no heatsink - i like to do the RC filter too ... i've designed similar but the single supply rectifier approach is very nice. I learned something from this design.
@MyVanitar
3 жыл бұрын
Thanks, actually what you see is not necessarily a final product to be used "as it is", so I only install heatsinks for testing purposes or no heatsink for this test, because the load is small.
@ovi_4
4 жыл бұрын
Hi, really nice designg and well done PCB. I like it. Tnx. However the next step in improving the design would be the so called tracking dual power supply style where you only need 1 adjustable potentiometer to adjust 1 rail only and when you do that then the other rail will automatically self adjust the very same voltage level. There are some old IC's that do that + short circuit protection as well but they are no longer manufactured and very hard to get. So it would make sense if you could design such a circuit with individual components and perhaps add some heat sink so the circuit can be used for current values that exceed 1A per rail.
@MyVanitar
4 жыл бұрын
Thank you very much for you suggestion. That's interesting, however in this design I also intent to address the cases where both rail are not necessarily identical. for example positive rail could be +5V and the negative could be -12V.
@zahiddogan
Жыл бұрын
How robust is the output voltage of the circuit to variations of the input voltage? For example, if the mains voltage drops from 230V to 180V, will the output voltage also drop by 20%?
@MyVanitar
Жыл бұрын
No. it depends on the difference between the input/output voltage. if the input voltage does not fall off this range, nothing will happen. you as a designer should predict such situations, if they could happen
@BruceMardle
4 жыл бұрын
Since this works with only 1 transformer secondary, I wonder why 2 are used so often. I'm planning to build a variation on this using an LM2940T-5.0 and an LM2990T-5.0 to give +/-5V outputs. Thanks for the design!
@MyVanitar
4 жыл бұрын
Thanks
@mahlonkarpaiya252
Жыл бұрын
Me again. Thanks for all the help so far. What I need is a 1amp power suply but wanted to ask if using bigger caps and removing r1 and 2(I have noted it will be more noisy) would slow for higher currents. Alternatively could I ask your assistance in drawing up a on 317 337 power suply that would allow 1 amp. Thanks a Lot for your help
@mahlonkarpaiya252
Жыл бұрын
Good day. I have bought 5 of your boards they work great. I have a problem with one of my powersuply and wanted a little advise. R1 gets really hot on start up. I am use a 3 wqtt 10r . I just wantedto know if the power suply would work without the resistors R! and R2. Thanks
@MyVanitar
Жыл бұрын
Yes, it will work, but the output noise increases. you can use resistors with lower values or short the resistor's footprint by a wire (jumper). This is actually an RC filter.
@MyVanitar
Жыл бұрын
This is mainly a low current, low noise power supply for sensitive circuits (using that RC filter)
@ignitionhighpowersound2753
Жыл бұрын
Thanks
@miguelaraujo1313
2 жыл бұрын
Nice but, ripple needs to be tested at maximum load condition and usable frequency but yeah I liked it.
@MyVanitar
2 жыл бұрын
Yes, this circuit has been designed for sensitive circuits and low current applications. check my other projects as well.
@radionicapcelica5322
Жыл бұрын
I need help sir. I have built lm317/337 psu and i don't have oscilloscope but only dmm. My ouputs are dead locked to +/- 15VDC as per my needs. But please tell me, is it normal to get 16mV AC on those regulated ouputs? To me 16mV Ac sounds a lot? Pcb is my own design based on VRDN power supply
@MyVanitar
Жыл бұрын
Did you design this circuit on your own PCB? The output should not be like the one you mentioned. if you get a high current from output, the noise level increases, but for low currents, you should not read that
@gino3286
4 жыл бұрын
Hi ! thank you very much for your excellent video ! i have at hand a preamp that needs +/-24V The present power supply is based on fixed voltage regulators providing negative e positive voltage. What would be your choice of circuit to get the minimum noise ? the circuit has low distortion already but noise depends a lot on the quality of the power supply of course. Kind regards, gino
@MyVanitar
4 жыл бұрын
Thanks Gino. In all power supplies, the output noise increases by increasing the output current, so if your load is an PreAmp, this circuit will work perfectly. However check the current consumption of your circuit for confirmation. if I remember I selected the input/output capacitors to be 35V or 50V, decide based upon your application. Since your load consumes low current, you won't need to keep the input voltage much higher than the output.
@gino3286
4 жыл бұрын
@@MyVanitar Hi thanks a lot for the kind advice. Do you sell the boards or the kit maybe ? or have a link to a seller ? as i said i would need a low ripple +/-24VDC power supply. I was thinking to buy a lap one but it is too big and the best ones are also very expensive units. The other option could be an additional regulation stage before the +/-24V stage in series. I am a quite undecided. The preamp in question is decent an old Bryston 0.5B ... it is low distortion but channels separation could be better i understand. Kind regards, gino
@CHRlSTlAN
4 жыл бұрын
Could you test the output voltage at maximal und medium current. With no load is every linear controlled power supply fine.
@MyVanitar
4 жыл бұрын
The output voltage does not get affected by the load (output current increase). More output current just means more output noise and this is true for all power supplies. regulators keep the output voltage untouched, however, increasing output current causes more voltage drop on components. for example you can not get 12V output from a 12V transformer at the input. So in such cases the input voltage must be higher to compensate the drop. V=R*I, so at 500mA output, a 10R resistor will case 5V voltage drop. Therefore this circuit mainly get used in low current and noise sensitive applications such as a pre-amplifier ... etc
@samhsavdr9647
4 жыл бұрын
good day i want to convert irobot roomba battery to li ion battery. This is a very common issue. How can I do charge voltage ranges from 7 to 20v .. 3200ma - 14.4v 5200ma liion battery
@MyVanitar
4 жыл бұрын
Replied you on another video
@lillyreyes2513
3 жыл бұрын
have you ever used a digital potentiometer ?
@MyVanitar
3 жыл бұрын
You want a digital control? yes it can be
@carunyazx950
4 жыл бұрын
👍
@abdulrazzak20_23
2 жыл бұрын
HOW MANY WATTS SHOULD MULTITURN BE?
@MyVanitar
2 жыл бұрын
Just check what I have used. very low power potentiometers.
@ohmware2020
4 жыл бұрын
does it have a short circuit protection???
@MyVanitar
4 жыл бұрын
Yes, LM317 provides. besides output current is limited
@CHRlSTlAN
4 жыл бұрын
Internal short-circuit current limiting und Thermal overload protection. www.ti.com/lit/ds/symlink/lm317.pdf?ts=1593186876030&ref_url=https%253A%252F%252Fwww.google.com%252F
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