Transistor belonging Data 1(yellow) in your scope capture behaves less accurate than the other one for sure. This might be originating from thermal effects or degeneration of germanium due to time interactions. To me these two circuits looks like they are synthesized for the same purpose only for different supplies. Can be some kind of trigger level adjuster to input another circuit as cascade. On Tue, Nov 1, 2011 at 12:29 PM, PETER ONION w= rote: > Is there anyone on here that has experience with germanium transistors us= ed in > logic circuits ? > > I'm having problems with some logic circuits from the 1960s that use OC42 > germanium transistors. > I've googled a bit and read about the issues caused by the "high" collect= or-base > junction leakage currents, but I'm not sure if the symptoms I'm seeing ar= e a > consequence of this or not. > > The devices are called "minilog" =A0and the circuit diagram (from the ori= ginal > documentation) of the "type 7" is shown at the bottom of > > http://www.peteronion.org.uk/803logic/minilogs0003.jpg > > I've put a capture from my 'scope on my web site at > http://www.peteronion.org.uk/803logic/WA000009.BMP > > It shows the inputs (bottom two traces) and outputs (top two traces) from= two > gates in the same package driven from a switch. =A0Logic levels are 0V an= d -10V. > As you can see about 2.5s after the falling edge on the output one of the= gates > output starts to drift up from -10V towards 0V. =A0I've also seen gates w= here the > drift starts ~1ms and rises much faster. =A0 As you can see there are no > capacitors anywhere in the circuit (other than junction capacitancies and= stray > capacitance between the components). > > > Any ideas on the cause ? > > PeterO > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .