Power supply negative rail

Valie

Member
2010-01-13 12:10 pm
Hi there, I built a 18 v -/+ split supply using 7818 and 7918 Ic`s. The wiring is correct on the smoothing capacitors(1000mf) on the intake side. When I measure voltages on the outputs I get 18v on the positive side and 24v on the negative side (no load ). Shouldnt it be the same voltage?
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
You'll probably find the mixer draws more than enough current to meet the minimum required in which case no resistor is needed.

The data sheet for the 7918 should tell you what the minimum current is, typically it will be around 3ma to say 12ma worst case.
 

Valie

Member
2010-01-13 12:10 pm
Thanx very much, you made my day. This is an Inkel MX 1600 mixer that I got without the external power supply. I had to trace a lot of wires to work out the circuits that is needed to get this thing working again. So far Ive worked out that I need 3 x 18v+/- rails, 1 x 12v
1 x 6v a/c and the 48v phantom supply. I should connect very soon. Thanx again.