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How To Work Out Parallel Resistance (If You're Completely New To Theory And Don't Get Maths)

December 10, 2012, 3:09 am
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First of all you need a Scientific calculator to "play along" I know the one in windows is adequate if you don't have one, I'm not sure what the Mac one is like but I'm sure it will be fine. I personally use a Casio Fx-7000G - it's from the 80's and it's ace - go on eBay and try and find one. I'll put a picture of it below.

Hope this helps anyone who has struggled with it.

Once you Have grasped it you can go test your skills HERE


Ignore the Numbers That's Nothing To Do With This Article

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Maxon OD-880 Overdrive Stripboard Veroboard Layout

December 18, 2012, 6:36 am
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Another guitar overdrive (groan) but it's a good type of thing to build when you can't think of original ideas and I am abit stuck at the moment so I thought I would find a schematic of this particular Overdrive and lash up a layout, build it and then post on here for all you people.

The original unit used 3 LM741 op-amps and I was very very tempted to just use a dual and a single op-amp instead but I know people get a bit funny about using alternative IC's and stuff even though it would sound no different, however I specifically laid it out in a way that I could make a little daughter board to use a dual op-amp rather than 2 singles to get better battery life out of the thing.

If you want to experiment some choice component values to alter would be C4, R6, R7, the signal diodes (1N4148) and R9




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Signal Injector / Tracer Stripboard Veroboard Layout

December 20, 2012, 12:01 am
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A quick but very useful project. I "designed" (I say designed, it's just a simple astable multivibrator with a basic transistor amplifier) 10 minutes last night and built it this morning basically to help fault find because I'm sick of having to fire up the function generator/scope when I just need a quick tester.
so as usual I will share it with you people.






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Making A Current Blasting Power Supply With Old ATX Power Supplies

December 28, 2012, 2:46 pm
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what is Current Blasting? I hear you ask..
Well sometimes when you have a fault with a piece of equipment it's not always easy to track down the issue - it usually comes down to a failed component that has shorted internally - a single failed component of possibly thousands so one method of tracking it down is blasting it with high current (at a low voltage)
It is quite a fun method of trouble shooting because most of the time the failed component explodes off the board, starts smoking or gets very hot.
so what's the best method of doing this? well get a high amp power supply which costs loads of money OR make one out of an old computer power supply.
You have probably seen people make power supplies out of these before for powering their projects which I don't personally think is that great of an idea because of the high current involved but you can use it for that if you wish.

The reason why these things are great for current blasting purposes is because the junked one I have (which is from a very cheap case that had a power supply on it) has a 5volt rail of 27 amps, a 12 volt rail of 13 amps and a 3.3volt rail of 25 amps. which as you can imagine is more than enough.

now for the usual "danger" crap...
I'm sure by now you're used to reading disclaimers and warnings to the point of being desensitized by it and it is easy to ignore these things.
but these things can be very dangerous so you need to take a lot of care when building/hacking these things. They have a lot of capacitors which may retain high energy even when the unit is unplugged. you NEED to make sure they are discharged before you start handling it - that goes for the filter capacitor on the IEC mains input - sometimes they don't have a bleed resistor and can discharge 240 volts (or whatever your local voltage is) into you which I can assure you bloody hurts.

2 Things you must be aware of to use these things

1. in order to switch it on you need to solder the Green wire to Ground (black wire) I suggest
doing this by means of a switch. The green wire will be labelled "PS" or "PSON" on the main PCB

2. some ATX power supplies need a minimum load to function which is around 200mA
to achieve this you must bridge the 5 volt and Ground terminal with a 22Ω resistor.

if you're interested in how this was worked out you can use ohms law
R(resistance)=V(voltage)/I(current) so you type into your Calculator
5 / .200 = 25 so you have the answer 25Ω and you round down to your nearest value which was 22Ω in my case


Anyway here are some pictures, if you have any questions don't hesitate to ask. 



Bare ATX PCB
very cheap supply I found in my shed


I found this on the net some time ago, I'm not sure who it belongs to so if it's yours let me know and I will credit you and your site

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My 30th Birthday.

December 30, 2012, 4:46 pm
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Not really an electronics post - I'm sorry but it is my 30th birthday and it's finally time I can get something off my chest that has followed me everywhere for about 15 years.
The backstory is this.

When I was in school we had form tutors as each year was split up into forms so that when we weren't in a proper class like science or something we would go to our form rooms and our respective form tutor would do a filler type lesson.
One year they mixed it up a bit so you got to do the odd form time with other form tutors one of which was Mr Saunders.

The other half of the back story is that one of the things I suffer with is known as OCD - basically you have a very obsessional thought and you have to relieve that thought by reassurance, which is mostly compulsive acts such as the one everyone uses to illustrate OCD "washing hands"
you wash your hands because there is a thought they are dirty but the longer you leave it, the more dangerous the dirt becomes and so on.
one major issue with me is that if and idea gets planted in my head it will cause me more and more distress/panic attacks and everything anxiety.

So what has this got to do with OCD, Mr Saunders and my turning 30 today?
well one day we had one of those form lessons which somehow got onto statistics - you know - pointless ones that people just talk about to sound like they know stuff. Mr Saunders then said
"there is at least one of you in this classroom that won't make it to your 30th birthday"
these are words that have haunted me every day of my life since he said that. I am sure it was just one of those throwaway comments that people make but unfortunately I was in the room when it was said

I do wonder if I would have been a completely different person now if I had never heard that or
whether there would have just been something else instead.
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LED Crossfader Stripboard Veroboard Layout

January 10, 2013, 12:19 am
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This was a request I got via email, they wanted the LEDs to fade in and out to mimic some aircraft lights rather than just turn on and off so I came up with this little circuit. he also wanted it to run from 12 volts - so it does.
I was going to use an op-amp at first but I thought a 555 would yield a more consistent result 





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Floating Power Supply For DVM Panel Meters Stripboard Veroboard Layout

January 19, 2013, 6:15 am
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this was another one done out of necessity really.
I needed to power a panel meter from the same supply as I was measuring.
I actually didn't have the meter to test it with however it powered a cheap Digital Multimeter which I imagine takes up more current than a panel meter.
I also tried to make it small enough to be glued onto the back of the panel meter. 




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9v Fast(ish) Battery Charger Stripboard Veroboard Layout

January 25, 2013, 6:44 am
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most of the chargers I own don't work fast enough - they take in the order of 14 hours so I thought "why not make one" since I have about 30 things with chargeable 9 volt batteries in them it would be nice to make a few of these. Anyway I wanted to make one that automatically cut off but it got a bit messy so I figured I would just drop the amount of current going into the battery so I could just leave it going for a few hours.

to work out charge time: hours = mAh / mA
example case: a 9v battery I have is rated at 150mAh
150 \ 50 = 3
therefore 3 hours

the LED illuminates when the battery is connected

the Transistor (BD135) needs to be heatsinked but the LM317 doesn't so if you're using a metal case you could just screw the transistor to the case and use that as the heatsink




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Amplifier Speaker Load Box 16 ohm For Direct Recording

February 2, 2013, 7:49 am
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I wanted to use my Bugera 6262 cranked up a bit so I thought I need to design a quick load box so I can unplug the speakers and put the line out into my recording interface and use software based cabinets.

There isn't a layout per se but I've provided a schematic and pictures - it is a very simple design so you should be able to follow it easily enough.
you will also notice that it uses 2 100watt 33 ohm resistors in parallel which will allow you to use amps upto 100watts or in my case (130watt) an amp not turned all the way up

you need twice the power rating on the resistors as indicated on your amp - ie if your amp is 50 watts you need 100watt resistors.








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Self Powered 9 Volt Bar LED Battery Tester LM3914 Stripboard Veroboard Layout

February 16, 2013, 11:18 am
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another cool little voltage monitor but I had some requirements - I wanted it to be self powered and have an onboard load so I could check any 9 volt battery with it.
this is for a active pickup system so the self powered part of the design wasn't hard to factor in as usable voltage is around 5 ish volts in the EMG's I have.

and Last of all I wanted to use the LM3914 (DATASHEET) cause I've got loads of them from another project I never got around to doing.

I used a 82 ohm resistor (switched in by pressing the push to make switch) this will allow you to test the battery under a normal load which will give you a better indication of the batterys chargethe 82ohm resistor draws almost 110mA

I have done a circuit like this before which was a 0 - 10v voltage monitor (HERE) but the difference between that one and this is that this one is powered by the battery you're testing and the other one though more accurate needs a second power supply.




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Yamaha NE-1 Bass Parametric EQ Preamp ( Nathan East ) Stripboard Veroboard Layout

February 20, 2013, 9:03 am
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I'm not feeling too well so I won't drone on about this + I'm going to watch Michael Mosley documentaries for a bit.
My friend has been asking me to do a layout for the Nathan East Bass Preamp since his got stolen at a gig some years ago so I finally got around to doing it - I had to reverse engineer from pictures on the internet and it has been somewhat a pain in the ass however it now works and sounds how it should.

one thing I should mention is that some people mod it by changing C4 from 47p to 220p ( I think so they can use it with their guitars. Anyway - enjoy.



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Sparky 5 Watt Amplifier Stripboard Veroboard Layout

February 22, 2013, 2:21 pm
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I thought it was about time to tackle something that's been on my todo list for a while and that is to make a follow up to the infamous Ruby amp (made by Runoffgroove.com) which is a popular circuit among the DIY community.

So I thought the best idea was to use an amplifier IC in the same family as the Ruby's amp IC which after an extensive 5 minute search on Texas Instruments website lead me to the LM384 (DATASHEET) which is a 5 watt mono audio amplifier.
it needs a minimum of 12 volts to run though I would run it at 15 volts

All the way up it goes into crazy distortion but before that it is a really nice sounding amp, you get a nice clean and then the louder it goes the more it clips - but nicely - I must do some sound clips!

it powers a 1 x 12" cab very nicely - I've not tried it with a 2 x 12" cab yet but I think it will be fine.

so I introduce to you the SPARKY Amplifier - why did I call it the "SPARKY"? fuck knows, I think it was cause I was watching that cartoon where the piano comes to life.






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Greg Fryer Brian May Treble Booster Deluxe Schematic Stripboard Veroboard Layout

March 20, 2013, 5:19 am
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this is one of the best treble boosters I've built and I've built alot of them being a Brian May fan.
this was traced from the circuit board and I have made 2 changes (that don't affect the sound)

1. in the original there are 2 power supply capacitors (47uf and 33uf) in parallel which was obviously used to keep production costs down - Greg will have initially put in the standard 100 uf capacitor but if his other pedals/products used 33uf and 47uf caps - it would have been cheaper to just parallel a couple of those up to get near enough.

2. the other change is that there are 2 10pf capacitors in series again this will be a production cost thing - it would be cheaper to use 2 10pf capacitors in series than adding 1 4.7pf cap to the build (if he used a lot of 10pf capacitors in other builds which he most probably will do.)

so with those changes noted: it sounds no different to the original unit but you can always swap them if you don't believe me.





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Nintendetar Guitar Fuzz Stripboard Veroboard Layout

March 28, 2013, 7:23 am
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This is something I made a long long time ago and subsequently made actual PCBs for which I still have but due to the fact my agoraphobia has reached such levels I can't post them anymore so I don't bother selling them. however it's a cool effect so I made a stripboard for it. I also Made an Add-on board a while back located HERE

or with the Oscillator Add On..



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Soft Latch True Bypass (Relay) Switch For Guitar Effects Stripboard veroboard Layout

April 10, 2013, 12:07 pm
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People often like to retrofit their guitar effects with "true bypass" switches but this usually means wrecking the pedal case by drilling holes in it and stripping out the buffered section etc.

Personally I don't like doing this modification, I like there to be a buffer because there is always a degree of signal loss in pedal chains but this is here for those who do like to do it.

as it uses a mechanical relay (which can be found at Rapid Electronics or wherever - the one I used is the 12v version of this one ) it is exactly the same as a true bypass switch and adds nothing to the signal.
it is quite small so it can fit in some pedals (like a tubescreamer) or you could use it externally to maybe bypass a whole group of pedals (or just one of course)

it's worth mentioning that this has many other uses such as controlling high power relays with a little tact/push switch and so on

NB: if you find you're getting misfire clicks you can make the capacitor a higher value - that part acts as a crude debounce - the higher it is the more stable it becomes but the slower you can turn it on and off but I found 220n was fine for guitar bypassing

hope you like.


Sorry - the component numbers don't correspond to the vero - I will rectify that at a later date 


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Adjustable Lab Power Supply With Current Limiting ( L200C ) Stripboard Veroboard Layout

June 20, 2013, 4:15 am
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it's been a while since I've done a new layout - I've been and continue to be ill but I thought I would try and do something so people don't give up coming here. so with a body full of painkillers etc. I designed this little power supply.
it differs to my previous power supplies in that it is an extended range one. IE it goes from 0 volts upwards rather than 1.2volts upwards.
the way this is done if by creating a negative reference voltage and feeding it into the L200C regulator.

this also has current limiting so you can set it to drop out if a circuit tries to draw more current than it should (due to short circuits etc.) which can avoid circuit catastrophes.

anyway here you go.



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Simple LED Flasher Stripboard Veroboard Layout

June 21, 2013, 4:55 am
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I've done LED flasher type circuits before on here but usually they were for something someone wanted so they did specific things like fade in and out and so on.

So I thought for a little 10 minute project I would do one of the very first projects I ever made as a little boy. I was very proud when I made my first LED flash. it's not like now where people just load up the "blink" sketch in Arduino. this is a proper old school relaxation oscillator.
my original one had a few more components but I've managed to whittle this down to 3 resistors, 2 transistors and a capacitor + an LED obviously.

this particular circuit is known as a relaxation oscillator and there's lots of theory and stuff behind that but in extremely simple terms: it charges a capacitor until something "disturbs" it. in this case the "disturbance" is the threshold voltage of Q2 (the voltage at which the Base conducts) this quickly discharges the capacitor which results in a short blink.
which looks nicer than the conventional square wave oscillator which the LED stays on the same length of time as it is off

everyone loves a flashing LED


if you get this reference then you're ace.

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Temperature Controlled Fan Controller Stripboard Veroboard Layout

July 17, 2013, 9:54 am
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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.




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Adjustable Mains Hum Notch Filter Stripboard Veroboard Layout

July 19, 2013, 11:56 pm
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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



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Poor Mans Audio Signal Generator Stripboard Veroboard Layout

July 28, 2013, 4:15 am
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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.




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