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I have a Led flashlight that runs on 4 AAA batteries. I would like to power it from a 12 volt DC power supply. Would it be best to use a variable voltage regulator or can I simply use a resistor to step down the voltage to avoid blowing out the Leds? Or is there a better way to accomplish...
This is my first attempt to design a circuit with a Triac. I'm building the attached circuit but I can't get it to work. I even tried a push button switch in place of the MOC3023 but still can't get the solenoid to energize. I know it works if I connect it directly to the 24 AC. I tried both...
I have a door chime that uses a 16 VAC 10 amp transformer to ring a chime using a solenoid striker. What type of pot can I use to adjust the voltage and the volume of the chime by reducing the force of the solemoid?
I'm getting back to work on this circuit. I built it on a breadboard like the schematic in my previous post. The problem I'm having now is to a shorten the activation of the led (about .1 second) while the time between each led in the sequence is about 1 second. Right now, each led stays on...
I've been modeling a little difference sequencer circuit for my doorbell. (See attached) Right now I am using some LEDs in place of the opticouplers for testing purposes. Before I go any further, I am having a little problem with the timing. When I start the sequence, the first output on the...
This is the design I came up with so far. I still have to add a regulator circuit to convert from the 16 VAC to 12 VDC to power the solid state part of the overall mechanism. I still need a little help with some of the AC/DC overlap areas.
1) What would be a good choice for U1 to take the AC...
Thanks, I installed the ground and the simulation works fine now.
There are 4 plungers that play a total of 8 notes when it plays the Westminster chime.
I think I have a circuit that will work using a 555 and 4017. I now need to figure out which opto to use to switch the 16 VAC to drive the...
I have been working in Multisim to understand how I could use a 555 timer and a 4017 counter to solve my problem. I seem to be having a problem with the LEDs just flickering. I simplified and isolated the circuit to just the 555 part of the circuit and still the LED flickers in simulation. I...
I have a set of vintage door chimes that uses an electro-mechanical sequencer to activate a series of plungers to strike the chimes. The problem is the mechanism uses a low rpm motor to sweep a set of contacts over traces on a PC board to sequencially ring the chimes. It has worn to the point...
I have a number of 18 volt battery packs for DeWalt cordless tools that no longer hold a charge. I had read somewhere that often only one or a few of the cells may actually be bad causing the entire pack to be useless. I would like to see if I could make a good pack by using the good cells...
I need a circuit that will close a relay (to sound an alarm) when the voltage in a 24 volt battery (2 - 12 volts in series) drops to a predetermined voltage. I'd like to be able to adjust the threshold voltage. I also plan to add a timing circuit to sound the alarm for a defined period of...
A follow-up question...
When resetting a series of flip-flops, does it make a difference if each has its own pull-down resistors (bottom circuit) or can they have them in common (top circuit)?
How's this? Does this eliminate the reliability issue?
Brad, should I also be able to decrease the "on" time by decreasing the size of the resistor? Is there a point at which increases and decreases no longer has a significant effect on the duration?
I've tried adjusting the 820 ohm resistor in simulation but it doesn't seem to give me a very wide range for adjustment. Why do you think it is not reliable? I've attached the original schematic I used as a basis. What would you suggest instead? Can you point me to another schematic? This is...
I'm working on a electronic combination circuit using a series of flip-flops. That last stage triggers a timing circuit that holds a relay closed for a set period of time. (I've attached a drawing of the circit below) Since I modeled this after some circuits I found on the internet and I'm...
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