With this circuit we can power small appliances which use 9V batteries from the power grid, with a good economy. This circuit is for appliances with currents up to about 50 mA. The advantage of this circuit over many eliminators is in the use of the transformer which provides safety and a zener diode regulation.
This circuit uses a 9 + 9 V secondary transformer with current between 50 and 200 mA. The zener diode is 1 W and in the output we must use a connector or plug according to the device to be fed. In Figure 1, we have the complete eliminator circuit.
The resistor R1 should have a dissipation of 1 W if the consumption of the appliance is high and tends to heat up. Note the polarity of the output connector. In Figure 2, we have the assembly using a terminal strip.
If the feeding device tends to rumble increase the value of C1.
Material list
D1, D2 - 1N4002 or equivalent - silicon diodes
Z1 - 9V1 - 1 W zener diode
T1 - Transformer with primary 110 V or 220 V and secondary of 9 V x 50 to 200 mA
R1- 220 ohms x ½ W- resistor - red, red, brown
C1- 100 uF at 1000 uF x 12 V - electrolytic capacitor
X1- Connector according to the power supply or plug
Miscellaneous: terminal strip, power cable, mounting box, wires, solder, etc.
