DIY pedal power supply, is there "too much" filtering?

[Nicko_Lps]

Came across this schematic on the internet, 3x4700uf seems awfully alot.

My version of it is 1x2200uf before the regulator and 1x200uf after. Both electrolytics bypassed by a film cap most likely 100nf or so

Im planning to use a 2x10VAC out EI transformer and get a 2 separated power supplies, one for before the preamp and one after the preamp.

Inrush current? Transformer stress? What can go wrong with so much filtering? Or more is better without any downsides

 

[Yaromeer92]

2000uF its enough for every 1A with 10v. Its Simple calculation. Nothing less, max 25% over it.
When you start your device these caps need to be filled with power. In that short moment they would drain a lot of current. When transformer is really weak this could destroy primary winding. But there is another factor. Secondary winding and core efficiency works like absorber.
Be carefull with L7809, just use huge radiator. Mine was burnt after few weeks. Then i used same chip with huge aluminium plate radiator and works fine.

 

[owlexifry]

Came across this schematic on the internet, 3x4700uf seems awfully alot.
View attachment 1140023
My version of it is 1x2200uf before the regulator and 1x200uf after. Both electrolytics bypassed by a film cap most likely 100nf or so

Im planning to use a 2x10VAC out EI transformer and get a 2 separated power supplies, one for before the preamp and one after the preamp.

Inrush current? Transformer stress? What can go wrong with so much filtering? Or more is better without any downsides

i don't really have an answer, but i built this one and it's awesome.
no issues.

(7812 + 7809 for 12V and 9V outputs)

sourced from:

Misc > The Ultimate Power Supply : DIY Fever – Building my own guitars, amps and pedals

[DIY Fever] The Ultimate Power Supply - heavy duty isolated power supply for all my effects

diy-fever.com

(i did box this up eventually lol)

 

[Nicko_Lps]

2000uF its enough for every 1A with 10v. Its Simple calculation. Nothing less, max 25% over it.
When you start your device these caps need to be filled with power. In that short moment they would drain a lot of current. When transformer is really weak this could destroy primary winding.

Thank you for the answer,

I should have probably mentioned it but i failed, i dont think i will ever draw more than 500mA 2nd winding and way less in the 1st winding, probably around 100mA. The transformer i found is 2x1A though so i mentioned

The question is... Because less ripple less noise from the power supply i assume, so you think 2200uf pre-regulator and 200uf after is more than enough?

(7812 + 7809 for 12V and 9V outputs)

This power supply is intended for a 4 channel EQ rack, ive seen people stating more voltage equals more headroom on the EQ and a switchable 9 or 12 volts supply would be a good idea.

Thanks for sharing this schematic i might do that!

 

[owlexifry]

Thank you for the answer,

I should have probably mentioned it but i failed, i dont think i will ever draw more than 500mA 2nd winding and way less in the 1st winding, probably around 100mA. The transformer i found is 2x1A though so i mentioned

The question is... Because less ripple less noise from the power supply i assume, so you think 2200uf pre-regulator and 200uf after is more than enough?


This power supply is intended for a 4 channel EQ rack, ive seen people stating more voltage equals more headroom on the EQ and a switchable 9 or 12 volts supply would be a good idea.

Thanks for sharing this schematic i might do that!

no worries
- should also have mentioned i used 12V AC tap off the transformer (rectifies to around 15.6V DC)

you could also do 15v with 7815 regulator if you use a 15v AC tap off the transformer (18v same deal)

 

[Nicko_Lps]

(rectifies to around 15.6V DC)

While not on load i assume?

I guess i have to take that under consideration as well because as i stated above i will never be able to load this transformer at its max capabilities

you could also do 15v with 7815 regulator if you use a 15v AC tap off the transformer (18v same deal)

After replying at your comment i started thinking that from 9VDC to 12VDC that "headroom" difference wont be great, now you mention 15VDC so you got me thinking again

 

[Splodgeness]

The 78xx series regulators have a repution for being very noisy, so a lot of downstream filtering could be needed to remove as much of this electrical noise from the supply line as possible. Try and find a circuit that uses an LM 317 adjustable regulator - they are not as noisy.

There is a good discussion here -

Lm7809 hiss noise

Hi, i am building regulated power supply for guitar effect (compressor). There is a bridge rectifier (db107) and a cap (4700uF). The regulator has 220nF at input anf 100nf at output. There is no hum, but a sibstantial hiss when I run the effect. Putting another 4700 uF at the regulator output...

www.diyaudio.com

 

[Nicko_Lps]

There is a good discussion here -

Thanks alot about this link, sadly the adjustable regulator seems to be harder to work with. The discussion you linked me had a great idea about using a low pass filter, maybe a choke filter as well