superheat6k
Well-Known Member
Confession time, but firstly nothing wrong with my maths.
My component laying and soldering to veroboard well that's another matter ...
1 Track to track short between the +VE Feed and -VE to the alt function.
2 +VE Feeder diode the wrong way around. The track short allowed the non alt indicator lights to function as though this was properly orientated.
3 Managed to tear a track whilst removing the veroboard assy from the box I had neatly drilled for the LEDs to poke through. Spent nearly an hour trying to work out why the buzzer would not work from individual alarms, but would work for the group alarm test.
Do the tracks on veroboard have to be quite so close together !
Now all working I can confirm the current through an indiviual LED in series with the 150 ohm resistor at 12 volts is 0.06 amps so about 0.72W just on the limit of the resistor. I left the pair with the 2W resistor on for half an hour - too hot to touch but nothing burning uncontrolably. In reality these lamps will only light for at most a few minutes at a time. I wlll need to add some small holes to the case to allow air to crculate to cool the 2W resistor, or perhaps a strip of copper wrapped around it to act as a heat sink.
Current through the 2W alt exciter resistor & LED / Resistor pair in parallel 0.25 amps so 0.19a through the 68 ohm 2W resistor. Allowing for the field coil resistance this shoudl work just fine as it is marginally higher tha th eoriginal filemant bulb.
The finished article will only need to use the original 9 pin connector block, and will be a lot neater than my previous attempts.
My component laying and soldering to veroboard well that's another matter ...
1 Track to track short between the +VE Feed and -VE to the alt function.
2 +VE Feeder diode the wrong way around. The track short allowed the non alt indicator lights to function as though this was properly orientated.
3 Managed to tear a track whilst removing the veroboard assy from the box I had neatly drilled for the LEDs to poke through. Spent nearly an hour trying to work out why the buzzer would not work from individual alarms, but would work for the group alarm test.
Do the tracks on veroboard have to be quite so close together !
Now all working I can confirm the current through an indiviual LED in series with the 150 ohm resistor at 12 volts is 0.06 amps so about 0.72W just on the limit of the resistor. I left the pair with the 2W resistor on for half an hour - too hot to touch but nothing burning uncontrolably. In reality these lamps will only light for at most a few minutes at a time. I wlll need to add some small holes to the case to allow air to crculate to cool the 2W resistor, or perhaps a strip of copper wrapped around it to act as a heat sink.
Current through the 2W alt exciter resistor & LED / Resistor pair in parallel 0.25 amps so 0.19a through the 68 ohm 2W resistor. Allowing for the field coil resistance this shoudl work just fine as it is marginally higher tha th eoriginal filemant bulb.
The finished article will only need to use the original 9 pin connector block, and will be a lot neater than my previous attempts.