Hello,

Here is detailed description of my project: system powers from 9V transformer which gives me about 13Vdc. This I use for relays. Then I regulate it to about 7.5Volts, which powers GSM phone. After that I use low drop regulator to power 8052 and MT8870. I want to use MC34063 instead of i.e. 7808 to minimize heat loss, since current (and so dissipation) can be high when charging baterry in GSM phone.

I tried to add 1N5819 in series with inductor. I will add optional filter, which I saw in new datasheet I found. The one I got did not have optional filter schematics. I have a bad feeling since I saw this ripple on the OUTPUT of 5volt regulator.

Yes, layout could be a problem. How to avoid ground noise? Do you have any app. notes on drawing ?


regards, Damjan