Fixed 22/33 kHz function generator

Thread Starter


Joined Oct 29, 2015
Hi, I require some help with a project to make my day easier.

I need to build two function generators, 22khz and 33khz.
Both sine wave
That will go through 5m of thin cable to earth.
At a constant 1mA, so I can trace the signal from above for test purposes.
Powered from any standard plug in power supply batteries not required.

I can find DIY kits but nothing seems to get to the KHz required.
I am no design engineer but have no issue building - could any body give me a point in the right direction please.
I know I can buy a complex sig gen but I want something with a simple switch that if broken wont hurt to replace.


Joined Mar 30, 2015
Google it. Are you sure you need a sine wave oscillator?

With square waves, you could use a 555 timer, 2 resistors, and 2 caps for each oscillator.

Thread Starter


Joined Oct 29, 2015
I am testing a 'cable locator' in radio mode which looks for 22khz then a simulated 33khz generated signal.
22khz is produced by telephone cables underground and 33 is when you apply external signals.

I want to build a simple test bed under concrete so users can quickly check there cable locators before the day's work so they know it functions - they have no tech skills and expecting them to use a signal generator is not reasonable

Cable locator example

Basically the signal is turned on the user runs there equipment over it and it should find the cable


Joined Mar 14, 2008
So what about a square-wave output, such as dl324 mentioned, which would be simple to generate?
It would have some harmonics of the fundamental included, but would that be a problem?

Thread Starter


Joined Oct 29, 2015
Yes I have been Google as suggested, and yes I think you and dl324 have a point, there are even some cheap off the shelf kits 'it was knowing what to google that helped'
The difference in harmonics wouldn't give any issues considering my needs,

Thank you both - big help :)