Well, there are a lot of bulbs that work with more, that's one alternative. Are you using xmas lights? But the other approach is to limit the voltage to the load (bulb) seaparately from the voltage supply for the overall circuit. Again, how are you powering this? what is your 2.25V source?
Ok, how's this one look, linear? I want the bulb to come on as light is shined on the photo-transistor. ignore the 1.7V for now, that's because i'm going to try this with both a bulb and an LED and see which I like more. for the record: -Is a T1 size LED 3mm or 5mm? -do the stripes on a capacitor mean (+) or (-)?
I'd run the circuit off 12V. Make your supply 12V and drop voltage to the load with a series resistor. Two good reasons: 1) you can get a free increase in your time constant (tau), since it varies linearly as R. Just make sure that the voltage divider works out to give you ~2V on the bulb, i.e. make the R in the ballpark of 47 ohms (about 5 times the bulb resistance). Now your tau just increased by a factor of six as well. Put the cap inparallel to the series combination of the bulb and the resistor. 2) if you want the bulb on as the light shines on the photoresistor, I'd swap it with R. But it occurs to me now, why not use a phototransistor instead of a photoresistor? you'll get almost everything you need for light-switching in the single package that way, all you'll need to do is provide a way to switch the load current.
I started working with these transistors here can someone tell me how to get them to act as an electrical switch, I can't get it right.
Just ignore some of the markings that aren't relevant to you: Put 5V where I've got labeled GPO+ and you'll get current flowing in the load.
So far I can't get the transistor to work the way I thought it would, isn't it suposed to take a small voltage as a tigger to turn on a switch for a larger voltage. Can you tell which pin is which. I know that NPN and PNP are very different items, but how does it effect the PIN layout. So far, just having two of the pins connected will supply power through the transistor, I've tried many combinations. Should I need the third pin to act as the switch?? Also, for a capacitor, if two are in parrallel, to their farrad ratings add? Ex. 2200uF and 2200uF in parrallel = 4400uF??
If its on all the time its quite likely that you have the Collector and Emitter the wrong way round. Try swapping the connections. Yes, if you have two capacitors in parallel then the combined capacitance is the sum of the two.
