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regenfreak · 16th Oct 2019, 12:33 am

Hi
I will need a B+ [HT+] supply of about 100-110V for a home built from scratch of an 3 valves strip version of an All American Five AA5. I am not ready to go for the valve rectifier yet in my early learning stage and I am conscious of the safety issues. I have the following components:

1) 150W 240V-240V isolation transformer

2) 240V-250V HT 160mA and 6.3V 4A filament valve transformer.

3) 20H choke 75mA

I have seen this battery eliminator 90V, 67.5V and 45V on ebay using two back to back 230V-9V transformers and an IC voltage regulator for the filament supply:

https://www.ebay.co.uk/itm/90-Volt-B...kAAOSwR0JUTlL4

I think the 6V6.uk battery eliminator uses the two 230V-6V transformers as cheap alternative to an isolation transformer, maybe it uses schematic similar to this:

https://antiqueradio.org/bsupply.htm

It uses different values of R3 to give 90V, 67.5V, 45V etc

I am interested in building my fixed 100V B+ battery eliminator using the most simple and reliable solid state rectifier schematic using fast diodes UF4007 to reduce noises.

The supply must be safe and resistant to any open circuit voltage rise ( happens with a swinging choke)and inrush current. And it should not be loaded down easily.

1. What would the best way forward if i use my 240v-250V valve HT transformer to build a simple and stable B+ of 100V with a current of 20-30mA? Shall i use a simple rectifier schematic with smoothing caps with a output voltage dropping resistor if I know in advance the total B+ current of the valves? Do I need to do trial and error to get the exact voltage dropping resistor value?

2. Anyone knows any schematic for vintage battery eliminator like this or similar? It seems the voltage output can be loaded down easily.

https://www.youtube.com/watch?v=x4lDIG_RNl4

I could have build a rectifier module plugged to an isolator transformer using a variac to have variable B+. The rectifier would have C-L-C choke filter. But I prefer a compact power supply and my 3KW variac is a heavy, bulky beast and I dont want to take it out of storage unless I use it for high power projects.

16th Oct 2019, 12:33 am	#1
regenfreak Heptode Join Date: Nov 2018 Location: London SW16, UK. Posts: 655	DIY battery eliminator for valve radio Hi I will need a B+ [HT+] supply of about 100-110V for a home built from scratch of an 3 valves strip version of an All American Five AA5. I am not ready to go for the valve rectifier yet in my early learning stage and I am conscious of the safety issues. I have the following components: 1) 150W 240V-240V isolation transformer 2) 240V-250V HT 160mA and 6.3V 4A filament valve transformer. 3) 20H choke 75mA I have seen this battery eliminator 90V, 67.5V and 45V on ebay using two back to back 230V-9V transformers and an IC voltage regulator for the filament supply: https://www.ebay.co.uk/itm/90-Volt-B...kAAOSwR0JUTlL4 I think the 6V6.uk battery eliminator uses the two 230V-6V transformers as cheap alternative to an isolation transformer, maybe it uses schematic similar to this: https://antiqueradio.org/bsupply.htm It uses different values of R3 to give 90V, 67.5V, 45V etc I am interested in building my fixed 100V B+ battery eliminator using the most simple and reliable solid state rectifier schematic using fast diodes UF4007 to reduce noises. The supply must be safe and resistant to any open circuit voltage rise ( happens with a swinging choke)and inrush current. And it should not be loaded down easily. 1. What would the best way forward if i use my 240v-250V valve HT transformer to build a simple and stable B+ of 100V with a current of 20-30mA? Shall i use a simple rectifier schematic with smoothing caps with a output voltage dropping resistor if I know in advance the total B+ current of the valves? Do I need to do trial and error to get the exact voltage dropping resistor value? 2. Anyone knows any schematic for vintage battery eliminator like this or similar? It seems the voltage output can be loaded down easily. https://www.youtube.com/watch?v=x4lDIG_RNl4 I could have build a rectifier module plugged to an isolator transformer using a variac to have variable B+. The rectifier would have C-L-C choke filter. But I prefer a compact power supply and my 3KW variac is a heavy, bulky beast and I dont want to take it out of storage unless I use it for high power projects. Last edited by regenfreak; 16th Oct 2019 at 1:03 am.