We found this circuit in a 1967 English magazine, but it can be assembled with minor adaptations, such as changing the transistors for more modern types. TR1 and TR2 can be BC548 and BC558. TR3 and TR4 can also be BC558. The speaker can be 4 or 8 ohms and power can also be made with 6 or 12 V according to the relay.
| Clique na imagem para ampliar |
