Function Generator

[floppybootstomp]

I'd been looking for a replacement since my commercial one died a couple of years ago. That one cost around £200.00 and I really didn't want to pay that much for a tool I didn't use that often.

A function generator produces sound waves and is invaluable in testing and repairing audio equipment, in case you're wondering. Some of you, of course, will be familiar with such a piece of kit.

I was looking around half-heartedly searching when I came across a kit in Maplins, of all places.

Here's a link: Only thirteen quid

I had a couple of CCTV 12V DC PSU's hanging about so I used one of those and the rest of the parts, including the kit, came to £26.00.

Only thing I'm not keen on is two push buttons to raise or lower frequency, would have much preferred a rotary knob. Still, for the price, this thing's great.

It produces sine; square; triangle and sawtooth waves from about 20Hz to 18Khz, which is adequate.

I put the kit in a case and as many of the functions were onboard, I flew them to the top panel of the case.

External functions are:

Audio out
Loudspeaker out
Frequency up and down buttons
Waveshape selector
Waveshape LED indicators
Loudspeaker volume control
On/off switch


The following pix show the waveshapes on my oscilloscope, the first one was with flash, the rest were taken without flash but I increased the display brightness on the 'scope.

So, if you need one of these, this is a nice cheap option that works :thumb:

[Agent]

Good post mate - very interesting

[Whiternoise]

I bought one of these for under 20 quid from eBay a while ago:



Works a treat for this sort of stuff (no square or sawtooth though)! Shame you can't do "exact" frequencies, but it's very affordable for what it can do.

[Rave]

I currently have no need for one of those, but I still fancy making one.

[GAteKeeper]

Whats wrong with the Mrk I Throat, tongue and lips + electret microphone? I can produce a nice range of frequencies in both sine and 'crud' forms.

na, nice little circuit did the ATTiny come pre-programmed?

GK

[TheAnimus]

if you want a 'nob' to turn, have a think about extending the project to use a rotery encoder (aka infinately twidly nob) and get into the wounderful world of micro programming. I was always a fan of the PICs rather than the ATs myself!

[floppybootstomp]

I bought one of these for under 20 quid from eBay a while ago:



Works a treat for this sort of stuff (no square or sawtooth though)! Shame you can't do "exact" frequencies, but it's very affordable for what it can do.

That's a good purchase

Had I realised such a thing existed I could have saved myself some time.

Still, it was quite a satisfying little project to make.

nice little circuit did the ATTiny come pre-programmed?

Yes it did. I put it together, switched on, held breath and it worked straight off. Which kinda surprised me

Thanks for the comments everybody