We have many versions of biofeedback with the 555 IC on this site. This is another one. We found it in October 1986 Radio Radio Electronics magazine. The power supply must be isolated.
The integrated circuit of this 80's project is not common today. This is the HA2530 which must be...
This circuit is from a 1992 PE Hobbyst Handbook. The circuit fires an old electronic flash using an...
This complementary transistor stage was found in a 1968 publication. The transistors are germanium types and...