I would like to produce a home made signal generator, with a built in counter. I have looked over the net, and even though I have a fairly firm grasp of electronic design, I am struggling with this!

I originally thought I could make it with discrete components, but after a few minutes, I decided that maybe a PIC based generator/counter would be easier. I have only a very limited knowledge of PICs, but I am trying to teach myself as I go along. I have the ability to program Microchip PICs.

The following are the specs of my design:

Sine-wave and square wave outputs;
Vout max: 20v (p-p) (variable down to <1v);
Frequency range: <10Hz - 1MHz (variable with clearly defined divisions);
Variable duty cycle;
Single shot step input button;
7-segment display output for the current frequency.

With discrete components, I'm pretty certain this is quite a task, but I'm hoping the use of a PIC greatly reduces the complexity. I'm not expecting someone to give me source code for this, but could anyone give me some useful advice. I can think of the general principle, but I'm not sure how to apply it.
Any help would be appreciated.

 

The Australian magazine "Silicon Chip" described one in January 2001.

I'll dig it out after lunch and advise.

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Len

 

It is not suitable as it has a maximum output frequency of 2 kHz.

It is simply a DAC driven by the parallel port of a computer.

Even the scope trace for the 1 kHz sinewave is a bit bumpy.

Have you considered a Wein Bridge oscillator?

You could use a PIC to measure the frequency and output it onto a 7 seg display.

I'll look further for suitable circuits later.

__________________
Len

 

A Google search for "pic dds" will yield lots of good hits, and you won't need a counter. The signal is created by direct digital synthesis (dds), and all you need is a readout.

__________________
Ron

 

I found the one I was looking for. It is in Silicon Chip May 2003.

1 Hz to 10 MHz. It employs a 16F628 and a AD9835.

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Len

 

I don't think this kit fits your requirements but I suspect it may interest other forum members as it takes much of the hard work out of designing and sourcing parts for the DDS portion of a project...

Here's a 1.0 to 60.0 MHz DDS sub-system kit from AMQRP for $28(USD) using an AD9851 DDS chip (sample, of course)... Control it using an MCU of your choice or from a PC parallel port using public domain software...

http://www.amqrp.org/kits/dds60/

Happy Holidays... Regards, Mike