DC-DC converter

47 DC-DC converter A. Bovee When using a digital measuring instrument with another electronic circuit jt is often necessary or desir- able to completely separate the supply for the meter from that for the rest of the electronics. The problem can be solved by using two separate supplies, but it can also be done using a single supply and a DC-DC converter. The type of converter described here is quite compact and can deliver a current of about 50 mA. ;"CHARGE D1..D4=1N4148 83554 small audio transformer (from a pocket radio) is also suitable. The frequency and pulse width of the circuit can be adapted to the type of transformer used by means of Pl and P2. Firing transformers give the best results at frequencies of about 100 kHz, while audio trans- formers usually work best between 0.5 and 40 kHz. The transformer must, of course, be connected with correct polarity. 5. 50 + E "DISCHARGE f 071P1+P2+R1+R21 C7 "CHARGE 0.7(P1 + R1)C1 "DISCHARGE - 0.7(P2 52)C1 The transformer secondary volt...