> 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
