I have built the Analog Metric SR50 variable shunt regulator.
I need 12v and 5v output which I can get when under no load, but if I connect a 5R dummy load to the output it drops down to 2.1v for the 12v one and 1.9v on the 5v version.
Where have I gone wrong or is there a problem with the circuit ?
Many thanks, Alex.
I need 12v and 5v output which I can get when under no load, but if I connect a 5R dummy load to the output it drops down to 2.1v for the 12v one and 1.9v on the 5v version.
Where have I gone wrong or is there a problem with the circuit ?
Many thanks, Alex.
Attachments
Do you use only one tx?
Yes, one TX with 2 off 15v secondary.
I will try to change the jumper wire for R1 and use 1R or 10R and measure there what's happen with the current, also you can play using a lighter dummy load, that's only to know if goes ok with other requirements.
Are you sure shunt regulator can support 2A or 1.5A?
I did put a 3.3R on the 5v one and 10R on the 12v one to limit the current then took them out when I could not get any more than 2v out.
The transistors are rated at 6A so should be OK.
3R3 & 10R for R1 with 5R dummy load, if voltage drops it seems your shunt regulator can't afford the current you want and drops the voltage.
It just seems strange that the 5v 5R load is only 1A and still restricted to 1.9v out which is why I wondered about the circuit ….
Do you have 15R or 20R dummy load to try?
Just tried a 20R dummy load and I now have 5v. Q2 is running at 65ºC and Q8 is cold.
That's because the difference in/out is 20V. Use the same 20R dummy load for 12V.
I will get some more dummy load resistors and have another play tomorrow, Thanks for your help, much appreciated,
Kind regards,
Alex.
Can some kind sole give me a bit of an explanation how the circuit works especially Q1.
It is supposed to be adjustable from 5-50v and a max current of 8A.
The adjustment is after Q1 and 2 so I am a bit lost as to where do I start trouble shooting.
I am not an electronic engineer but have a good grasp of basic electronics and know how to use a multimeter and scope.
The AC transformer is 2 off 15v 100VA and I want to have 12v 2A and 5v 1A.
Many thanks, Alex.
It is supposed to be adjustable from 5-50v and a max current of 8A.
The adjustment is after Q1 and 2 so I am a bit lost as to where do I start trouble shooting.
I am not an electronic engineer but have a good grasp of basic electronics and know how to use a multimeter and scope.
The AC transformer is 2 off 15v 100VA and I want to have 12v 2A and 5v 1A.
Many thanks, Alex.
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