We found this circuit in the Radio Electronics magazine of May 1977. The transformer voltage is 6 + 6 V, and the current depends on the zener diodes and is in the order of 100 to 200 mA.
This amplified circuit was found in a magazine for radio amateurs 73 of the 90s. The circuit uses an...
The circuit shown is from the 1993 Motorola Linear Interface ICs. The power source may be common...
This circuit was found at Popular Electronics. The speaker is of the greater than 100-ohm...