17-05-2011, 02:08 PM
Thyristor pre-reg variable DC lab PSU's were quite popular in the 60's, 70's and early 80's. I have a few examples, the Farnell H series was quite notable for this technique. I have a Farnell H30-100, 0-30 volts at upto 100 amps !! This is a real monster, even with the pre-reg which limits dissipation in the pass reg by some margin, it still weighs 90KG !! The TX is massive, around 280mm square. Also have the H60-25, 0-60 volt at upto 25 amps, about 40KG from memory. They are superbly built units. Also have a Solartron from the 60's which is SCR pre-reg, thats quite early for such a technique.
I bought the Farnells when I was doing some experimental work on high performance car fuel pumps. May seem strange but when a turbo engine is pushing numbers like 750 BHP it needs alot of fuel !! Pumps capable of maintaining upto 60 PSI and 600-800 ltrs per hour they need alot of current. Initially I thought the H60-25 would be fine but when I saw pumps routinely drawing 20 amps I knew I needed something much bigger. Which is where the H30-100 came in, that coped ! The facility to vary and maintain high supply currents within fine limits allowed me to plot flow -V- pressure graphs for prospective pumps and also test for thermal stability.
I've seen some pumps draw 70 amps, which at a nominal 14 volts is about 1.3 HP !!
Noise has been cited as a problem with these SCR pre-reg supplies but I've scoped the output of the H series units on full load and there is less than most true linears !!
I bought the Farnells when I was doing some experimental work on high performance car fuel pumps. May seem strange but when a turbo engine is pushing numbers like 750 BHP it needs alot of fuel !! Pumps capable of maintaining upto 60 PSI and 600-800 ltrs per hour they need alot of current. Initially I thought the H60-25 would be fine but when I saw pumps routinely drawing 20 amps I knew I needed something much bigger. Which is where the H30-100 came in, that coped ! The facility to vary and maintain high supply currents within fine limits allowed me to plot flow -V- pressure graphs for prospective pumps and also test for thermal stability.
I've seen some pumps draw 70 amps, which at a nominal 14 volts is about 1.3 HP !!
Noise has been cited as a problem with these SCR pre-reg supplies but I've scoped the output of the H series units on full load and there is less than most true linears !!
