I used to gouge out and replace those bulbs in the RK05. The original
part was all in one piece, emitter and receiver, but later they made the
emitter part easy to remove and I kept one re-lamped in my kit for a
quick change.
I still had a pack of them a year or two ago, but donated them to the
National Museum of Computing at Bletchley Park in England. If Sean is
on this list maybe he can read the part number off the package.
cheers,
Nigel
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
On 2023-01-19 22:54, Marc Howard via cctalk wrote:
Most white LEDs are really blue LEDs with a thin yellow phosphor coating
(the eye sees yellow as red + green). I doubt they have much energy in the
IR range.
IR LED is probably the way to go. How hard is it to get to that bulb?
Marc
On Thu, Jan 19, 2023 at 4:02 PM Paul Koning via cctalk <
cctalk@classiccmp.org> wrote:
On Jan 19, 2023, at 2:46 PM, David Gesswein via cctalk <
cctalk@classiccmp.org> wrote:
On Wed, Jan 18, 2023 at 12:42:26PM -0600, Jon Elson wrote:
On 1/17/23 21:18, Marc Howard via cctalk wrote:
Does anyone know if that light bulb is still available? I’m not sure
what
the response of that photo sensor is and that might rule out using a
led
replacement. The fact that the bulb is almost certainty driven below
the
rated voltage also complicates matters.
If you need JUST ONE badly enough, you can probably keep it going.
Likely
an LED could be used as a substitute. But, a roughly equivalent bulb
with
the wrong base could likely be found and hacked.
Originally discussing RK05 head position sensor bulb. I have replaced
it. The
offical part to replace it isn't available. You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of
the
small ones with wires. It doesn't use bulb with base. LED didn't work. I
think sensor is IR.
Hard to know what the sensor wants given that it isn't described in any
DEC documents I could find. The schematics do mention that the light bulb
runs on +5 volts, which suggests that indeed it might be below its rated
voltage.
If the sensors want IR you could try an IR LED. Or a white LED on the
theory that it's a broadband light source...
paul
