Struggling with signal generator and counter!

[canadianpoet2012]

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.

 

[ljcox]

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

I'll dig it out after lunch and advise.

 

[ljcox]

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.

 

[Roff]

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.

 

[ljcox]

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.

 

[Mike - K8LH]

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...

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

Happy Holidays... Regards, Mike

**broken link removed**
**broken link removed**