This circuit appears in similar versions elsewhere on this site. The transformer is 110 V or 220 V input and 5 to 12 V output with current up to 250 mA. The transistor can be a BD136. R1 adjusts the frequency.
![](/images/stories/cir/2251252023_150205_0001.gif)
This circuit appears in similar versions elsewhere on this site. The transformer is 110 V or 220 V input and 5 to 12 V output with current up to 250 mA. The transistor can be a BD136. R1 adjusts the frequency.