Triple Pulse Generator using cheapish parts

[Peterae]

Hi
I have been very interested in reading about the TPU, and decided a while back to start experimenting, i Love to dabble with Pics and decided to start building a control unit, i felt pic processors are ideal, they are cheap , easily programmed and instead of building loads of different hardware you can change the programming.
I have used the PIC 12F629 it runs at 20Mhz and has an instruction cycle of 200nS and is only an 8 pin Dil.

The following circuit consists of 4 Pics, 1 is the master control, it sends timed pulses to the other 3 pics for syncronizing the pulses when doing frequency sweeps.
there is a button for shutting down all 3 generators, and an led to indicate they are on.

Using code in each frequency generator it is possible to set static frequencys or using a pulse generated from the control pic it is possible to sweep the frequencys on each pic generator synced to the master pic.
The on time and off time can be programmed giving a PWM pulse out on one of the pins, this is then fed to a FET driver and finaly a FET.The Fets are mounted on Heatsinks.

Using minimal parts it is possible to build a pic programmer, this is only a couple of transistors, caps and a 9 pin serial socket, the programing software is free, as is the code assembler.

So for very little money you have an easily configurable system, of course you need to be able to write assmebler code, even this is very easy once grasped.

I am putting this up just incase anyone wants to build it, it is only a prototype so far, and i am in the early stages of testing it, so there maybe changes to the circuit or board over the next few days.


I will put a picture up off the build board later.


Peter

[z_p_e]

Nice job Peter.

Should be helpful and appreciated by many here.

Have you seen these threads?
http://www.overunity.com/index.php/topic,2071.0.html
http://www.overunity.com/index.php/topic,2263.0.html

Darren

[Peterae]

Hi Darren
Thanks, nice to hear from you, i suppose it's fairly easy for me to make this stuff as im setup with a light box for making boards, i always proto type my stuff using etched PCB as it is quiet a fast and tidy way of making virtualy anything you want.The Pic again makes good sense for me to use, they are only about ?1.00 each have endless functions only limited by the software.
My main problem is i am just itching to build some TPU coils to hook up 
version 1 of the above board was a single channel driver, i soon realised i needed a triple version for experimenting, and also came to the conclusion it would be nice to get them sweeping the frequencys to aid looking for a sweet spot, hence a pic for controling the 3 channels.
It would also be fairly easy to build a cutout system into this to shut down if overload conditions arise, no doubt i will see ashes before i come up with a way to impliment that function, i have thought about using a hall sensor connected to a pic pin checking for large amounts of magnetic field and trip the channels before the nails get pulled from the floor boards .
The other thing which this should shine is the ability to de tune and monitor the control frequencys.
I am not sure at the moment how the PICS will behave with copius amounts of RF noise floating around, i suspect that SM was using analogue phase shifting IC's used in the early tv's for line timebase generation, The problem with using these instead of digital closed loop systems is that they would stray if too much noise was introduced into the system , i suspect that was his biggest problem in producing a control system.With the pic the only thing that can shift is the crystal oscillator and even that situation can be monitored inside the pic, if the external crystal stops an interupt is generated and an internal oscillator takes over operation.

The PIC processor has a reduced instruction set and has only 32 instructions to learn.

I have built the PCB and powered up last night, need to runn some checks put the fets in, and continue to get the code done.

The Links you posted are very interesting, He's done a very good job, i was looking at rs232 comms but decided against connecting up to the computer because of toasting the pc LOL, in the past i have used infra red comms port to pc from the pic but we are getting a bit to complicated, so i am trying to keep it simple for now.Hell if we can get a TPU working, i will design a Watt hour meter showing how much energy we are pushing out and connect a TFT screen to it blowing kisses to the person that crack it.

Peter

[Thedane]

Isn't it overkill to use 4 pic's to generate 3 signals?

Personally I'd use a single uP - in my case an Atmel ATmega 32  (Got dev. tool + debugger  )
http://atmel.com/dyn/products/product_card.asp?part_id=2014

Throw a couple or 3 AD9833's on a serial line
http://www.analog.com/en/prod/0,,770_843_AD9833,00.html

Display and keyboard is straight forward - and a little code --> Nice ACCURATE function generator. (Sine, Square, Triangular and PWM)

A fast power op-amp to drive FET's or transistors - and you're set to go.

I really like CodevisionAVR from HPinfotech
http://www.hpinfotech.ro/html/cvavr.htm
It is avaliable in a trial version, and together with Atmels AVR Studio 4 it's nice and fast to develop.

Just my 5 cents 

[Peterae]

Hi Thedane

The AD9833 looks good, now i could hang 3 of these off a pic quiet easily.I am looking into this at the moment.

Peter