Warning!
This power supply circuit uses 120 volts household mains and should only be attempted by someone that has the knowledge and skills to safely construct such a project. Otherwise personal injury and or property damage could result.

Test Bench Power Supply Schematic Diagram Complete.

Test Bench Power Supply Schematic Complete. The left side outlined in yellow is one of two power supply circuits. On the right is the relay delay circuit.


Power Supply Parts List

BR1 - KBL405 Bridge Rectifier or equivalent

C1 -  4700uf Electrolytic Capacitor
C2 -   0.22uf Capacitor
C3 -   22uf 35V Electrolytic Capacitor
C4 -   0.1uf 35V Capacitor

D1, D2, D3 - 1N4002 Diode
D4 - 11DQ06 Schottky Diode

IC1 - LM 317K Regulator IC

R1 - 240          (All resistors 1/4 watt)
R2 - 12K*
R3 -  1.5K*
R4, R5 - 2.2K
R6 - 1K  (2 watt)

VREF - LM385BZ - 1.2

AC Receptacle and or Power Cord
Banana Jacks 
F1 - 2A  Fuse
Indicator Lamp - Line Power (120VAC)

BR101 - DF06

C101 - 1 nf
C102 - 47uf
C103 - 100uf

D101 - 1N4002
D102 - 11DQ06

Q1 - 2N2222  Transistor

R101 - 680K
R102 - 100
R103 - 2.2K

RLA101 - Potter & Brumfied KHU-17D11-12

SCR101** - 276 - 1020 (Obsolete Part)

S1 - Toggle Switch SPST
S2 - Toggle Switch DPDT

T1 - Power Transformer(s)

LED1 - LED Output Indicator

** The NTE5465 is listed as a replacement for the RS 276-1020 in the NTE cross reference.

Other SCRs with lower current handling capabilities could be substituted to drive the relay used for this power supply project. The 276-1020 was the only SCR I had in my parts inventory.


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