This filter, with a cut-off frequency of approximately 1 kHz, has a high Q and employs two operational ones. The power supply must be symmetrical.
This circuit is from Motorola documentation on 1976 power devices. SCRs are powered according to...
Assembled with SMD components this spy can be made very small. We found it in an Australian...
We found this circuit in an old documentation. The operational amplifier of the time can be...