The explained adjustable power supply 3-30V 3A is a stabilized (regulated DC Power) power supply intended for testing just about all circuits in general, according to a stabilized DC voltage of 30 volts
This particular power supply was made as an auxiliary or as a long term power supply for many common circuits structured on stabilized DC voltage between 3 and 30V so long as the consumption is not going to surpass 3A. Needless to say, this power supply model could also be employed for various other requirements. By exchanging the trimmer with a potentiometer, it could quite possibly be applied as an variable power unit. A high quality heatsink must be employed for the IC and the BJT used in this circuit.
R1 = 8.2K
R2 = 2.2K
R3 = 680R
R4 = 1K
R5 = 82K
R6 = 0.18R / 5W
C1 = 470p
C2 = 100nF-63V
C3 = 100nF-63V
C4 = 100uF 63V-
C5 = 10KuF-60V
D1 to D6 = 6.6A
Q1 = MJ3001 (Darlington)
IC1 = UA723D
Overload protection is built-in
Short-circuit protection also included
Output current not to exceed 3A at the input
Output Ripple Voltage may not be higher than: 0.5 mV
Output voltage is linearly adjustable from 3 to 30V, stabilized
Input voltage should be preferably from 9 to 30V AC (depending on the desired output voltage)
Mounting inside a metallic cabinet
In case a metallic box is utilized, the tramsformer should be attached to it firmly with nuts and bolts for safety purposes.
Make certain that the heatsinks used doesn’t touch the metallic box. This may result in a short circuit.
While installing a toroidal transformer, it should be observed that the fixing bolt doesn’t come in contact with the box. This may result in the transformer to burn up
When the circuit is required to be incorporated into another box make sure, it is designed with ventilation gaps (you possibly can make yourself by drilling a handful of these holes), essential to relieve the developed heating.
How to test this 30 V variable power supply circuit
Hook up a voltmeter to “GND” the points and ‘+ OUT “and set” RV1 “until the preferred output voltage is arrived at.
Utilize some heatsink compound paste to the bottom of the transistor and attach it on the heatsink.
When you need 3 to 8 volts in that case R2 will likely be 5.6K
Should you need greater than 8 volts in that case the R2 is going to be 2.2K
The recommended transformer for this Adjustable power supply 3-30V 3A circuit must have the rating of 30VAC to 120VA