Hi Bill, yes the controller completely turns off the bulb, the voltage across the bulb drops to zero as measured by me. There is a difference in performance characteristics I notice, due to the power-supply (that which plugs into the mains and outputs the DC 12V for the dimmer's input) used. For the prototype I used an old manually switchable power supply that was able to output a range (discreet not continuous that is) of voltages from about 3V to about 14V. Using this PS the dimmer again turned the bulb completely off, but the bulb only started to work with the dimmer's 'dial' turned to about 25% on the dimmer's scale, and worked as expected from there up to the maximum.billbillt wrote:Hi John,
My last post seems to have disappeared.. I am anxiously waiting to see how the 5W G4 bulbs work out.. I once did a comparison test with a 2W G4 bulb vs a 50W halogen... The 2w lost out on brightness.. I was thinking... Half of the G4's COB LED's are on the back side... Maybe a small mirror placed there could help reflect the light towards the front.. Does your dimmer completely turn off the bulb? I have some of the same dimmers here and they do not completely extinguish the light.. I think these controllers are PWM devices... The beauty of all this is it is so inexpensive a person can experiment to no end...
The Best,
BillT
When I used (as in the finished version) the new PS (bought online for £8) at a single 12V 'for LED lighting' the dimmer was/is now able to start the bulb from it's 0% position, again smoothly up to 100%. Also the new PS runs almost cold, hardly any heat at all in this new system, either in the mains PS or the bulb in my scope's 'field-illuminator' housing.
I can only conclude from this that the new £8 'LED power supply' is genuinely a very good device for LED control and is of a very good build and operation standard - I think I got very lucky for the price - the 'special' PS was in this case worth every penny I think.
A really cheap & easy conversion, looking forward to when the new 5W (also dimmable) LEDs to arrive.
The lamp-housing and mount that held the original halogen has as you may imagine a (very basic but polished by me some while back with metal-polish 'til I could see myself in it!) built-in reflector - it's a cheapo piece of what looks like Aluminium.. So, I should get a reflective contribution also, from those LEDs not facing directly up into the field-lens. I think! I could always take such a reflector from some other bulb or torch etc and simply fit it beneath the 5W easily enough also...
I really like the new LED, it's far nicer to use and I no-longer fret over my slides being cooked anymore, especially as they are often 'still wet' when first observed! Cheap & simple, works very well!