About switching 12 volt DC four times a second.

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Tinkeret

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I'm completely helpless when it comes to electronics. But still I need to build something and I need your help. I need to switch 12 volts from the positive side of a car battery four times a second: that is, on and off four times a second. I've seen wiring diagrams her devices that do this, and I suppose they're simple but I can't make sense out of them. I can't make sense out of any circuit diagram. Is there a pre-made module it would do this? The amperage would be 4 amps or less at 12 volts. Thank you for any help you can throw my way.
 
That is, 1/8 of a second on, 1/8 of a second off, and so on, until the battery runs out of juice. Sorry, I keep thinking of ways to refine my question.
 
Okay I'll do it your way. I'll go to circuit City, get a breadboard, and all the parts. It'll be a first for me. Yours is by far the most helpful response I've gotten asking this question. Thank you.
 
Why do you want to destroy the car battery? It is never completely discharged.
 
What are the loads you are switching on/off ? LEDs, Filament bulbs, motors....?

Here is approach using block language (mBlock) to program an Arduino Nano board :

You drag and drop blocks into right hand window, config their parameters, like pin number
or voltage test. It would be easy to measure with Nano board Vbatt and shut off operation
when Vbatt drops too much. If you want I will show you the change in blocks to do that.

I added on/off switch. Read the comments next to blocks to follow how its working.
mBlock converts your block structure to Arduino code and programs the board.



if you look at the code basically when Nano board starts up first thing done is to make
sure output is off. Then you see forever block which runs the code inside its arms in a
loop. Inside loop on/off switch tested to see if its on, if so the load is turn on, then off,
for 1/8 sec on the 1/8 off, and loop repeats. If on/off switch off force output off.



To handle the current use a Arduino type relay board, or MOSFET .



OR relay board -



They come in 1 - 8 channels depending on how many loads you want to switch.

The Nano can take up to 20V input from vehicle power. But beware use a "load dump" circuit
to protect everything. Load dump cause large transient voltages in a car.

Google "car load dump protection circuit"

Boards, Relays, Alliexpress, Banggood, eBay....

Board + relay/MOSFET + Button ~ $ 6 to $8.


Regards, Dana.
 
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There are many timer modules on ebay. A programmable one that repeats continuously and has a relay output is around $10 US.

ak
 
audioguru said:
Why do you want to destroy the car battery? It is never completely discharged.
Click to expand...
The battery won't be destroyed. I'm using this circuit to deter bears from repeatedly ripping apart my wooden trailer looking for treats, even though I don't put anything in there that smells good to them, but who knows bears can smell anything. So I'll have it set up with an automobile ignition coil powered by a 12 volt battery, and have the ground wire from the coil connected to the battery and also to a few galvanized wires laying on the ground at the bears area of interest. The deterrent will be galvanized wires placed on insulating standoffs, originating at the high voltage output, strategically placed so the so the bear will contact them with his nose, and momentarily activate the circuit. They will just hang there not connected to anything, just waiting to be grounded so they can dump their the load. The bear will walk up to his item of interest, stand on the grounding wires, and touch his head to the high voltage wires. So when is activated it'll draw 4 amps from the battery for one or two seconds, then the bear will leave, and probably come back again to test it, get shocked again, and leave again. I assume this will draw very few amp hours from the battery per week. I'll be sure to keep the battery fully charged at all times. I don't know, but I may have to insulate the ground wires from the soil.
 
 
Please see my reply to audio guru. I really do appreciate everyone's help, and I like the schematic you posted for me. However I don't understand it. Will you please hand draw a schematic of this project as I described it to audio guru, labeling all of the parts in terms that I can understand (such as resistors of certain value, whatever a gate is, etc). This device only does one thing, so the schematic has to be really simple. If you do this for me it would be a HUGE favor. There are appropriate electric fence chargers for sale near me, but they're way too expensive. I'm on a fixed income and inflation is eating me up, so I figure a used ignition coil and some electronic components will be much cheaper so that I can afford it. Plus it'll be the first circuit I ever built and will be a lot of fun. I live way out in the sticks on two acres. This device will also allow me to raise chickens. Everybody up here uses fence chargers around their coops, or the bears would just rip the coops apart.
 
You need more than just an ignition coil and and on/off switch to make an electric fencer.
Do a search for "electric fence" on this site for starters.
 
I have just put one together using a auto ignition coil, typically a 555 timer is used, in my case I used a 8pin picmicro.
Mine is aimed at deer, one method is to use silver foil smeared with peanut butter on the live conductor wire, I am sure it would work the same for bears.
 

A Homemade Fence Charger, Energizer Circuit – Homemade Circuit Projects

www.homemade-circuits.com

555-ignition - Simpler

A circuit using a 555 timer that gives pulses to a mosfet, driving an ignition coil making a spark plug spark. To potentiometers make the pulses for the spark plug variable.
www.circuitlab.com

High Voltage Ignition Coil Supply

High Voltage Ignition Coil Supply: In this Instructable I will teach you how to build a High voltage power supply using an Ignition Coil.This project uses a 555 timer based circuit.We use a 555 IC because an ignition coil needs a squire wave signal to power it. so basically the 555 t…
www.instructables.com

Super Simple Ignition Coil Drivers

Super Simple Ignition Coil Drivers: An ignition coil (or spark coil) is nothing more than a low frequency auto-transformer with a relatively high turns ratio. The transformer typically has only a dozen or so turns on the primary but many thousands on the secondary. It is very compa…
www.instructables.com

555 timer ignition coil at DuckDuckGo

DuckDuckGo. Privacy, Simplified.
duckduckgo.com


Those links might get you started. Once you home in on one ask forum for
any recommended changes to make design more robust.


Regards, Dana.

Added -

555 timer applications sourcebook, with experiments : Berlin, Howard M : Free Download, Borrow, and Streaming : Internet Archive

158 p. : 22 cm
archive.org
 
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Nothing in the ignition coil circuits activates them. They are turned on all the time that the on/off switch is turned on. A motion detector circuit could be used to turn them on.
 
I used a 0.1 sec burst of pulses every second.
i.e. 1 second off between bursts.
BTW, 10kv is the maximum voltage per international rules.
 
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