E^2, I'll give it a runthrough and see what should be on a "little" board to isolate the big bad world from the delicate innards of the ULN 2003.
What I did for X2-7 was put a diode cross the relay coil in my Drake L-4 amp as that coil puts out over 400 V on the back voltage. The coil is driven by a 30 VDC supply and draws 50 MA when the transmit line is grounded. What else do people have in amps? Control line specs? I know there are already several widgit boxes on the market for the amp control interface. We need to have the rest of the input/outputs protected and incorporate the amp control in one plugin. 73, Larry K2LT drakerepair.com 800-687-9161 > > From: "ecellison" <[EMAIL PROTECTED]> > Date: 2005/11/20 Sun AM 01:59:34 WET > To: <FlexRadio@flex-radio.biz> > Subject: [Flexradio] RFC - Poor Man's Universal Controller Board > > Folks > > > > I think I blew the ULN 2003 open collector chip out of my radio during the > Belize DXpedition by trying to connect a relay in an amplifier directly into > the radio on x2-7 without any buffering. Perhaps a spike or surge. Dunno. > But it brings back to mind a project I suggested to Tony - KB9YIG who has > done a fantastic job designing and refining kits for the SDR-1000 and is > currently totally immersed in the SoftRock40 SDR. > > > > At one time I had suggested a "Poor Man's UCB" to connect dedicated and open > pins to the X2 15 pin connector. It was shelved and deemed not necessary > since users can plug just about anything into the X2 connector and > experiment. > > > > As a result of my experience, I'd like to 'throw' out an idea to create an > inexpensive PC Board to protect the X2-7 output to control Amps etc, with a > 5 v relay and provide jack for a cold switch to ground for X2-10 PTT input. > X2- pins 1 thru 6 could be brought out on a 6 or 10 pin Berg connector for > readily available ribbon cables to interface the control lines to some > external device, like a universal controller board or for experimentation by > users in a breadboard. Having a little external board connected to the X2 > connector perhaps with opto isolators would be a lot cheaper than replacing > the ULN - 2003! > > > > Anyone like to comment or tackle the design or parts for this board? Let's > kick it around a little! > > > > Eric - AA4SW > > > > > > > > >
