SparkFun Forums

[AlanDogg]

Hi folks,
I'm looking for a circuit diagram to build a pcb with the following spec. It needs to be 12vdc input and a 10vac output. would require 400ma max any help in the right direct would be much appreciated

[skimask]

Frequency?

Low voltage oscillator running at X frequency, a/c coupled to an opamp (TCA0372 comes to mind, but might not be the right one for this application), gain of 2-ish to get your 10VAC.
3) Profit???

[AlanDogg]

Hi Skimask,
Its for a friend who has a cattle prod which he uses when working with animals on his farm and has gone duff, They only last around a few months and the guy who sells them to him keeps charging for replacement but gives no warranty which is getting to be ouragious I thought i could make him a repalcement or uprate the compnents so its stable and last longer. I wont be profiting from this but its a challange as I havent made a pcb since collage (few years now)

The main board has cold tar poured on it so cant get to the duff components to repair it. I did remove some tar to get at the ic's and found the following ...

1x HEF40106BP
2x LM384 5W

I cant duplicate the diagram due to the other components being covered and not getting true readings for values. It also has a charging circuit via mains transformer and runs portable via 12dc rechargable battery. Output voltage is via a 10k variable resistor and imkaging it runs at 50hz

[lyndon]

So what's the 10VAC for? It's certainly not the output of a prod. Electric fences for horses & cattle output north of 5,000 volts at much less than 400mA. Even dog fences are 750V+

[AlanDogg]

Hi Lyndon,
Yes you are correct its not for fences or similar! Its a prod thats get inserted up the animals anus to paralyse the rear leg on the side that is being clipped to prevent kicking. It blocks the signals from the animals brain and prevents serious damage to the farmer. 10vac and 400ma is enough to do the job not intending cooking the animal (Well not for now) lol

[AlanDogg]

Any suggestions guy?

[lyndon]

Look at figure 2 here: https://www.fairchildsemi.com/an/AN/AN-118.pdf

1. Build this oscillator for whatever frequency you need at a 10V power supply level.
2. Use a leftover inverter (there should be 6 in a standard package) to invert the output
3. Use an L293 as a power driver. Feed one input with the uninverted output of the oscillator, and the other input with the inverted output. Now at the outputs of the L293 you will have a 10 volt p-p square wave that can drive up to 1A output.


Or go with skimask's suggestion above since going by the parts on your board, it's the same design he is suggesting.

[Dave Mueller]

I built one a long time ago, very simple, but couldn't find the schematic (or the box!). I just ran across something very similar while doing an unrelated search.
http://www.aaroncake.net/circuits/inverter.asp. An isolation transformer would give you a 1:1 ratio (approx), or you could step up then back down, or find a transformer with dual primaries and secondaries and wire the primaries in parallel.

I also thought of an audio oscillator followed by an audio amp in the 5 to 10 watt range. Although, I'm not sure how closely the impedance of a cow anus matches an 8 ohm speaker!