This generator is very simple and with the right parts it can to mount in a matter of minutes. According to the scheme (see figure) it is a asymmetrical multivibrator, transistors of different structures: n-p-n (VT1) and p-n-p (VT2). The generator is loaded to high impedance head phones BF1 type TONE-1, TONE-2. I turn it on push-button switch SB1 - it could be, for example, a Telegraph key. In this embodiment, the generator will help to study Telegraph alphabet: "points" would be consistent with a short press on the handle key, and a "dash" is more prolonged.
If Telegraph key will not appear, his role will perform the usual bell button.
The second application generator - "continuity test" installation. In the Jack x2 need insert the wires with the probes on the ends. Probes will touch check chains. If the connection is there, you will hear the sound in the head phones, with a cliff the chain doesn't make any sound.
In place VT1 can be set any transistor of the series N - N, and the place VT2 - any of the series MP39-MP42.
The generator is operable at a voltage reduction of the battery power GB1 to 3 V. When wish the tone of the sound it is easy to change the selection of the resistor R1 or capacitor C1.
Author: Belov