Hello,

I have a small battery backed up 8052 project. I use simple circuit for power supply: transformer 220/9 1,25A, greatz, capacitor and 7806 voltage regulator. After 7806 is anti-reverse diode 1N4001 and 4,8V Ni-MH cell.

Problem is when transformer is powered on or off, I get spikes on +5Vdc. I tied 47nF capacitor parallel to primary winding. I got rid of spikes when transformer turns off. I still have problem when turning on. I have a whole bunch of 100nano's in my circuit. But still my 8052 resets. As a watchdog and brown out detector I use tc1232.

Do you have any suggestions?

regards, Damjan