Poor Mans Audio Signal Generator Stripboard Veroboard Layout

this is something I made in school 15 odd years ago. you had to take a square wave, use a passive filter network to convert the signal to triangle and sine - this also has square and integrator waveforms. it's quite good up to 1 KHz but after that it starts to clip and go funny but it's more than adequate as an extremely cheap audio signal generator using 2 transistors and 1 LM555 timer IC - if you've gone through alot of my projects you'll notice how useful this IC is by now.

I have done another signal generator project that uses a proprietary ICL8038 IC Project can be found HERE which is more fully featured as far as project function generators go but the IC can be costly in certain places where as you can go on the grey market (IE eBay china sellers) and pick up hundreds of them for next to nothing.

Adjustable Mains Hum Notch Filter Stripboard Veroboard Layout

I built this for those of you who have guitars with single coil pickups or indeed anything that picks up mains interference up (that annoying set of speakers in my bed room for example) anyway this little device reduces the mains hum by several orders of magnitude

it is adjustable between 45Hz and 90Hz so just put it before your amp or whatever and adjust the trim pot till the hum goes away.

it uses the same Texas Instruments TLC071 OP-AMP as I used in the last project for pretty much the same reason

Temperature Controlled Fan Controller Stripboard Veroboard Layout

I built this for 2 things - 1. my computer is getting a little hot and I like quiet for as much as is possible so having a little automatic controller turning on a few fans when it gets too hot is ideal for me. and 2. my homemade power supplies could do with fans and again I don't want them running all the time but with this particular temperature sensor LM35DT as it is a TO-220 package you can screw it to the heatsink you have your regulators on (with the usual isolation of course) so the fan only runs when the regulator gets abit hot.

(v)R3 controls at which heat the fan will turn on at however it is a little tricky to calibrate so it will be a case of trial and error unless you have known heat sources.

I also used a TLC071 OP-AMP for a couple of reasons 1st. it is a single supply op-amp so I didn't have to piss about with dual supplies etc. and 2nd I got it free from Texas Instruments excellent sample service

I used a TIP41A because that's what was nearest to my hand. I know the schematic says TIP41C but it doesn't really matter - the letter designations just refer to the voltage the transistor can handle and none of them go below 40 volts so use whichever you can get or even any similar NPN power transistor will be fine.