Very stable 9VDC supply

[Colas LeGrippa]

Hola amigos, over the last weeks, I had time to experiment with power  supplies, I destroyed some builds I made, I kept some.
A couple of years ago, I had bought a dozen of 16VAC  transformers and I wanted to use them in some kind of project. I found out that the most stable power supply for pedals was the one shown in the picture. It yields 9.4 V - 9.7V at 1 A and the three pedals that I connected to it did not lower its voltage. The schem. does't use a LM 7809 but rather a TIP 41transistor.

[Latole]

I use this ;

https://addison-electronique.com/produits/alarmes-et-securite/unit-d-alimentation-r-gul-e-3-a-0-24-v-cc/

[Latole]

1A $25 CND

https://addison-electronique.com/recherche/?term=unité%20d,alimentation%20régulé

[sluckey]

Here's my 9V pedal board supply. Good for 3 amps. Currently powering 9 pedals without breaking a sweat.

[Colas LeGrippa]

Interesting. I don t know that 123K transistor

[Colas LeGrippa]

Latole, c est bennn trop cher j ai tout ce qui faut ici pour les fabriquer

[sluckey]

Interesting. I don t know that 123K transistor

The LM123K is a 5V 3A regulator chip in a TO-3 case.

[Latole]

Latole, c est bennn trop cher j ai tout ce qui faut ici pour les fabriquer

J'en ai eu quelques uns gratis.........

You are right, it is less expensive if you build yourself

[Colas LeGrippa]

Hey Steve, I don t get that one. 5V regulator yielding 9 V ?

[PRR]

> 5V regulator yielding 9 V ?

Do you see the extra resistors?

However it appears the LM123 (any flavor) is out of production?

[sluckey]

Hey Steve, I don t get that one. 5V regulator yielding 9 V ?

Easy. That regulator puts out 5V in respect to the "Reference" pin. If the reference pin is connected to ground, you get 5V out. But if you put 1.3V on the reference pin, the output becomes 5V + 1.3V = 6.3V. Or, if you put 4V on the reference pin, the output becomes 9V. Or, if you use a voltage divider on the output, as I did, and you put a pot in the voltage divider, you can adjust the output voltage to what you want, within reason. In all cases, the voltage between the output and reference pins will always be 5V, but the voltage between the output pin and ground will be the sum of 5V plus whatever voltage is on the reference pin.

The simple zener/BJT series pass voltage regulator you have has been around since the dawn of transistors. It works very well but lacks any overload protection. Short the output to ground (touch the positive and negative leads together) and you will kill the transistor and possibly damage the rectifier and transformer. This short can also occur due to a shorted filter cap inside one of your pedals. My LM123K and the 7809 have overload protection built in and will gracefully shut down if an overload occurs, thus preventing any damage to itself or any other upstream components. When the overload condition is removed, the regulator will happily come back to life.

Sometimes simple is not better.

[Colas LeGrippa]

Impressed.
Thanx for your extended explanation. You 'll send me a bill for the electronic lesson


PRR, sure I had seen the resistors but I wasn't sure if they were part of a voltage doubler circuit or what. My knowledge of electronic theory is quite limited you know. I know how to build good sounding tube amps though.


Regards