Wednesday, November 30, 2011


I thought a bit about the electronics for the console panel. I want to be able to control it remotely from a PC. The PC will need to be able to record input from toggle switches, buttons and rotary controls (potmeters and rotary switches). It will also need to be able to switch the lamps on and off. In total, it will have to provide 183 digital inputs, 237 digital outputs, 5 analog inputs and one analog output (for the voltmeter).
I've opted to use a Velleman K8061 kit. This is a USB interface that provides 8 digital inputs, 8 digital outputs, 8 analog inputs and 8 analog outputs. To control the multitude of switches and lights, I'm going to use shift registers. Lots of them.

The lamps are a bit of a problem. After testing them I found that about half of them are bad and won't light up. They're tiny incandescent bulbs in a plastic casing that plugs into the sockets on the panel. I haven't been able to find replacements for them. Also, the incandescent bulbs would need a buffer stage to connect them to CMOS logic.

Fortunately, the casings are not too hard to open, so I think I'm going to open them up and replace the bulbs with LEDs.

I've just sent off the order for electronics parts to my supplier. I've ordered the Velleman interface kit, a power supply, veroboard, shift registers (74HC595 and 74HC597), orange LEDs, ribbon cable, connectors and a lot of other small items.


  1. Actually ... those are NOT incandescent lights. They don't 'glow' from hotness. They are miniature neon discharge lights. The take like 'no' current to go (of course they do.. 0.01 mA) but a significant voltage: more than 100V
    Denk ook aan een 'spanningzoeker' !

    Google found some for sale @ Ebay


  2. Hi Hein, good to see you here!

    I'm afraid you are mistaken. Other IBM machines did use neon bulbs, but these lights really are incandescents. There's a filament in each bulb, and the half of them that still work light up around 8-9 volts.