The simplistic Salas low voltage shunt regulator

[roender]

Originally Posted by Salas

Golden section.

Golden plated PCB? (BiB)

[Salas]

Immersion gold indeed.

Spandau Ballet - Gold live at IOW Festival 2010 - YouTube

[Dr.H]

Probably looking to run 25V, 18V, 10V; I assume 250mA will be the sweetspot for all of them?

[Salas]

250-300mA if you are sending up to 100-150mA to the load is good difference. With those parameters you are OK with the standard transistors. Use 5K trimmer with 1k2 series resistor in its tail and it should cover that range.

P.S. Hey where are some pics?

[Dr.H]

My initial refleKtor was a rough rats nest. I am designing a pcb in eagle and will post pics of board once populated. Do you have a ready pcb layout? I would iron it to pcb and etch.

[Salas]

I have got double layer with on board rectification and filtering. Maybe you can follow some ideas from it though. If you will have your raw DC part on a different board add a decoupling capacitor across the reg's board input.

[Dr.H]

Thanks Salas, I tried last night and ended with a mess. Will use yours as a guide. How important is the heatsink on the M1. I understand the need for one on M2.

[Salas]

Very important. Remember you burn total CCS current times (Vin-Vout) on M1. You burn Vout times (totalCCScurrent-loadcurrent) on M2. Do the power calculations for any setting conditions in each app you got in mind and estimate thermals and sinks.

[Dr.H]

Thanks, will design tonite.

[RCruz]

Originally Posted by AndrewT

The added resistor that Roender is recommending goes before the first smoothing capacitor. (do you remember my rCRC recomendations?)
It can go between the rectifier and the smoothing cap or between the transformer secondary and the rectifier. Both of these locations are before the smoothing.

The PSU can be a simple C, or a CRC ,or a CLC, any of these work and all will work with the added R.

That added R is the reason I do not use big thick cables to connect the transformer to the PSU and through the PSU. I used to do that (40years ago) before I stated to think and simply copied what I saw others doing.

Just because you see something 100 times does not mean it is right. Sometimes what you see only once is better.

Hi Andrew
Would you care to elaborate on the Whys of using thin wire or using some resistance after the tx ?