What type of component does this?

[carl1864]

I'm looking for a simple type of component that I can put in a basic circuit, that will complete and break the circuit many times real fast. Probably between about 10-30 times a second. The current would be from either a AA or 9 volt battery. Is there any type of basic component, or simple circuit that will let the full current from a AA or 9 volt through in pulses, about 10-30 pulses a second? Perhaps a way to adjust the pulse rate too? thanks.

 

[ke5frf]

Yes, a transistor driven by an oscillator, a 555 timer, a microcontroller PWM, etc.

Some will have gradual, nonlinear transition from on/off, (sine wave) some will have nearly immediate on/off (square wave) or some will have sharp, linear switching (sawtooth).

Google 555 timer, transistor, oscillator, etc.

 

[carl1864]

I like the idea of the transistor driven by an oscillator, since it sounds simple. What size transistor and oscillator would I need for use with a AA or 9 volt? And is there any way to vary the pulse rate? Like to vary how fast the oscillator oscillates?

 

[ke5frf]

Wow, well it depends on a huge variety of factors.
Any of the 2N series (ex. 2N2222 NPN, BJT) will work, but depending on the application and specs will require different current limiting, biasing, etc. The load (what is being switched on and off?) and the desired frequency, acceptable phase shift, power usage, etc will all come into play. Oscillators can be be varied with R-C components, crystals, etc. You'll need to decide if you want to go the FET or BJT transistor route, and you'll need to understand why...advantages, disadvantages.

Look, being that you are asking what is considered a fundamental question about a fundamental device, I can only assume that you have no idea what you are doing. To say the least, it would take writing a book to explain all you need to know to design this yourself. My suggestion is that you build something that is already a proven design. There are PLENTY, I mean PLENTYYYY of free schematics on the internet. All you need is a search engine and computer. The keywords I suggested will drop a million webpages on your lap. You will need to decide what method of wiring this up you favor. Breadboarding, board etching, or point to point construction. You will have to learn the proper method for these techniques.

I can only get you started by sending you to Google to find the circuit that is reputed to do exactly what you desire.

A hint: There are oscillator ICs (integrated circuits) that pretty much do it all within one component, (a chip) with having to only add a handful of external parts and the power supply....typically a few capacitors, resistors, some protection diodes, and possibly the output transistor(s). But you'll need to determine your needs and the load specifics even with this, choose the correct IC, and learn to read the datasheet to properly fit the external components...that is unless you find an exact circuit to fit your needs on the internet and simply build it per instructions.

 

[ke5frf]

Simplest_LED_Flasher_Circuit

This is a 12 V LED flasher circuit to get you started. 8 AA batteries in series gets you 12 volts, and you can get battery backs in series configuration for the project.

To flash the LED at the rate you desire, you will change the value of the capacitor to a lower value. You might try 50 uF or so to speed it up. At 20-30 Hz (flashes per second), it will be only barely detectable that the LED is flashing to the human eye. 20 Hz is not fast as electronic circuits go, but it does borderline the rate that the eye can register.

 

[microtexan]

Are we talking a "Taser circuit" here Carl?

 

[carl1864]

Thanks for the help ke5frf. Yes I am pretty much a newbie, although I have recently spent many hours reading and learning things, probably about 40 hours of reading, as well as making simple curcuits as of recent. Despite all that reading, I just could never find the answer to this particular problem.

As far as if its a taser circuit, I don't think so. What I'm trying to make is the equivalent of one of those toy shock lighters. I want to keep it safe and low current, but high enough voltage to feel.

The way the shock lighters work is they are simply powered by a small battery that goes through a transformer. The transformer acts like an electromagnet, so as soon as its charged up, it pulls a strip of metal towards it which breaks the circuit. That piece of metal vibrates very fast, which causes the pulsed DC. The problem is those little vibrating metal switches fail too often and are very unrelable, a small drop or something knocks it out of wack and it no longer operates properly, so I want to replace it with a different component such as the oscillator of 555 timer.

Would the blinking led circuit work for this application? I had researched blinking led circuits as a possibility before, but I didn't think they would work, since most of them have resistors in the series. Wouldn't that be counterintuitive, since you would want the full battery juice to pass through the circuit to the transformer? They also have capacitors, which I was thinking I'd probably not want in a circuit since I want it to remain safe and low voltage, wouldn't want a capacitor suddenly discharging or something. All the 555 timer led flashers I read about were the same way, they had resistors in the chain, so I figured that might be limiting the current going to the coil.

Obviously I have a lot to learn, but I was starting to think perhaps the oscillator/transistor route might be the simplest, since its only 2 components, and since the oscillator would give the pulses to the transistor, and transistor would allow the full current through.

What do you guys think?

 

[crutschow]

The transformer acts as a inductor and the inductive kick can generate very high voltages when suddenly switched off, which is what generates the shock. For this application you will need a high voltage transistor and likely a zener or transorb type device across it so it doen't get zapped. The needed parts voltage rating depends upon how high the voltage actually is.

How much of an arc does this device generate? Does it jump a gap? If so, how much of a gap?