I'm currently building a 50V power supply for my Dad's vintage telephone exchange equipment.
We need a 50v 5A unregulated supply to operate the system so I decided to build one.
The equipment uses a lot of large electro-magnets, coils, relays that pulse operate.
I decided that a linear PSU would be a better choice as appose to a switch mode under these quite harsh current-fluctuating circumstances.
I purchased a suitable 500VA torodial transformer (2x 115v input and 2x 50v output)
I've put the 2x 115v inputs in series as our mains here is 240v.
The AC output on each of the 2x 50v taps is over 50v, but was expecting a drop after the bridge rectifier.
I've actually added 2 separate bridge rectifiers, one for each of the outputs, effectively giving me 2x 5A supplies.
The DC output from each of the bridge rectifiers is nearly exactly 50v - so far so good.
The problem i'm having is when I add filter capacitors.. I've added a 10,000uf 100V electrolytic across the DC side of the bridge.
After doing so the output voltage jumps up to 72v.
I wondered if someone could help explain what's causing this and possibly how to remedy it?
Its still at around 72v under load of about 1A.
Dan
We need a 50v 5A unregulated supply to operate the system so I decided to build one.
The equipment uses a lot of large electro-magnets, coils, relays that pulse operate.
I decided that a linear PSU would be a better choice as appose to a switch mode under these quite harsh current-fluctuating circumstances.
I purchased a suitable 500VA torodial transformer (2x 115v input and 2x 50v output)
I've put the 2x 115v inputs in series as our mains here is 240v.
The AC output on each of the 2x 50v taps is over 50v, but was expecting a drop after the bridge rectifier.
I've actually added 2 separate bridge rectifiers, one for each of the outputs, effectively giving me 2x 5A supplies.
The DC output from each of the bridge rectifiers is nearly exactly 50v - so far so good.
The problem i'm having is when I add filter capacitors.. I've added a 10,000uf 100V electrolytic across the DC side of the bridge.
After doing so the output voltage jumps up to 72v.
I wondered if someone could help explain what's causing this and possibly how to remedy it?
Its still at around 72v under load of about 1A.
Dan