Fading LEDs / Eyes for Halloween decorations stripboard veroboard layout

The inspiration for this little circuit with Halloween approaching was a post I saw made on this Thrifty Crafty Girl
basically the girl had an idea of putting glow sticks in toilet rolls with eyes cut out to leave in bushes however I thought it would be cool to add an electronic element to it.
so I made a little circuit that will make LEDs fade in and out - they will go in and out of sync and will look pretty dam creepy
Anyway this one quite cheap to make circuit will "power" 4 toilet roll monsters - 2 LEDs per toilet roll or whatever you want to put "eyes" or LEDs in
below is a video of it in action

Paul in the
Lab is here to help
Everyone that's into electronics
Always feel free to
Seek my advice
Either using the
Contact button or my email
Lately I am always at the computer because
I am  designing stuff for the site though I did buy a new
Camera recently it's pretty cool. I remember the first thing I built was the
Knight rider LED scanner which I uploaded
To the site a few days ago, remember if you need to know
How to do something
Even if you think it's
Abit of a stupid question just ask, I
Don't mind. We all had to
Start somewhere. 

Voice Bandwidth Filter for podcasts / youtube veroboard stripboard layout

This idea came about when someone was tweeting on twitter that they were having problems with rumble noise and high pitch squealing from some air conditioner unit. So I thought I would make a filter for people to combat such problems, basically this thing attenuates anything below 300Hz and anything higher than 3KHz which is pretty much everything outside of the vocal range.
This could be a useful thing to combine with the high quality Microphone Preamp I designed some time ago located HERE

It's been a while since I posted a project because as you (may) know I build up things before I post them so I know they work however I've had bugger all money to buy stripboard, I actually had to de-solder an old project to get enough to prove this one so if anyone can help me out with some stripboard I'd be most grateful!

Paul in the
Lab is here to help
Everyone into electronics
All ways feel free to
Seek my advice
Either using the
Contact button or my email
Lately I am always at the computer because
I am always designing stuff though I did buy a new
Camera recently, I remember the first thing I built was the
Knight rider LED scanner which I only
Added a few days ago, anyway I
Digress, hope you enjoy my
Site

anyway here is the filter

Knight Rider Kitt / Cylon LED Sequencer Stripboard Veroboard Layout

This is a cool little project I've been meaning to do for a long time. One which was so simple I kept putting it off.
Essentially this is a 8Hz (ish) squarewave generator attached to a decade counter - it counts upwards displaying each count on the next LED however the outputs are wired in such a way that instead of just going upwards it goes back downwards. it should be obvious when you look at the schematic how the thing works.

Anyway as the name suggests the LEDS go back and forth like the eye things on Cylons from battlestar galactica or the front panel on the car from knightrider. my older brother drives a taxi so I plan on using this to drive relays to big lamps and attach it to his car when he's next away.

This circuit is very useful outside of replicating old TV show LED things, you can use it to sequence pretty much anything using relays or even digital circuits and you don't have to use the 555 to do it automatically, you can replace that with a push switch circuit to the CD4017 Clock pin (14) and control a pedalboard for example
or maybe even make your house seem haunted by using it to remotely control appliances. I will include a simple Relay Driver below.

 

To use the CD4017 to drive a relay

Mosquito Repellent Stripboard Veroboard Layout

I'm pretty ill at the moment and I didn't want to really get up let alone make a circuit however the reason I am ill is because of bastard mosquitos - you see they bite you and your body reacts to the bites as it would a virus and with an illness the actual feeling of being ill is your body attacking the illness. in most people this reaction lasts a very short time and you don't notice it however with me any illness I get prolonged reactions, I always have which is why I feel really ill right now.
So in order to stop it happening again I thought I would make an electronic mosquito repellent

it mimics the sound the pregnant female mosquito makes which warns others to stay away.

RIP Hans Camenzind

sadly, the inventor of the 555 timer IC passed today

Dual Tracking Power Supply Stripboard Veroboard Layout

another project born of necessity (ie I blew my other one up) This is a 1.5Amp dual polarity power supply (adjustable)

This may look like a waste of stripboard however once you see how big the 1000u caps are you will realize that you need the room.

6 watt desktop amplifier stripboard veroboard layout

I wanted a nice powerful stereo amplifier for studio use, I'm pretty sure this will drive a few pairs of headphones/speakers though I've only tried it with one pair.
this would also be well suited for a nice set of powered monitors for a laptop or any other application.
anyway, I found the TPA1517 from Texas Instruments and it works great.

the powersupply needs to be very clean maybe even external to the unit itself. you'll notice there is a resistor across the terminals of the big capacitor (4700uf) this is a bleed resistor and its purpose is to discharge the capacitor once it is powered off, with the value stated it takes about 3- 4 minutes to discharge the 4700u 40v capacitor. it's not a necessity but it's advised to avoid electric shocks - even the 40 volt cap I used packs a nasty punch.

when you turn it on don't have your headphones over your ears - this is very very loud so the input signal needs to be raised very gradually

Audio Function Generator Stripboard Veroboard Layout

there isn't really much to say about this circuit as it is mostly a 8038 based function generator with a few bits added on such as a DC-DC convertor for the bi-polar power supply and a range/shape selector switches etc.
the ICL8038 is rated to range from 0.0001Hz to over 300KHz however the sine on the one I built up stops becoming useful at about 300KHz and it starts at about 10Hz however this maybe because I exclusively use parts from broken stuff - the IC was harvested from a PEAVEY classic chorus amplifier that died years ago, The pots came from an old mixing desk and so on so you may get closer to the rated range however 10Hz to 300KHz is fine for most if not all Audio applications.

I should also mention the LT1054 DC-DC converter, I got this as a free sample from Linear Technology and I used this over the more common MAX1044/7660 ICs because I need 12+/- volts and the 1044 has a maximum rating of 10 volts.

Notes:
The ICL8038 does get quite hot
Make sure the capacitors are all rated at 35volts or above

Linear - Log etc. Potentiometer Conversion

sometimes it's not always possible to get the response you want from an existing potentiometer and sometimes like me, you don't want to have to keep buying loads of different types of potentiometer
or you're just too lazy to reach upto the draw with the log pots in and the linear ones are nearer, whatever the reason you can alter the response curve using the following schematics - I didn't bother doing a stripboard layout for these because it's pretty much 1 or 2 resistors - I tend to use resistors the same value or higher than the pot value however you can bias the curve response to one side or the other using lower values that the pot.

anyway experiment until it does the right thing, that's the best way

White Noise Generator Stripboard Veroboard Layout

This is a very basic circuit which consists of 2 parts
1st is the noise generator which is the first transistor with no collector connection
2nd is the bit which may look more familiar which is an AC common-emitter amplifier and this is just to bring the noise upto a usable level - I have taken a scope screenshot of what the noise looks like however it is an audible sound which is pretty useful for testing guitar fx or filters and other such things.

if you wish to learn more about the common-emitter amplifier the best source for information is "The Art Of Electronics" book - on page 77 almost the exact same amplifier circuit appears with explanation 

you can of course experiment with different types of transistor in the noise section - i'm not sure how available the BC108s are now, I just happened to have a load of old ones, I hit it with a hammer to get a bit more noise out of it.

the best voltage I've found to use this at is 18volts however it does make noise at 9volts upwards