Easy HiHat/Snare Circuit

Ruebezahl

Working on a modular Drum Machine i am collecting some nice but easy to build Drum Modules right now. On youtube i found this seemingly super easy Circuit, wich i want to use for a hi hat.

https://www.youtube.com/watch?v=B8t38IFALTo

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So i built it after this schematic, but it wont really work. there is some ticking sound, more than just the tick from the clock, but its also not really a hihat. Do you see anything on the schematic what could be wrong?
Are the diodes used in this circuit critical? I used 1N914instead, but that shouldn't be a problem, right?

Thanks for your help

elmegil · Posted: Thu Aug 07, 2014 8:28 pm Post subject:

You built it with three transistors, right? I'm not sure how clear that is....

Ruebezahl · Posted: Thu Aug 07, 2014 8:46 pm Post subject:

Yeah, i did it with three transistors, and the left one connected, in the way as its shown there, i.e. Emitter on top, Base connected to the Base of the other transistor and collector unconnected.

elmegil · Posted: Thu Aug 07, 2014 9:41 pm Post subject:

The trigger diodes definitely should work fine with 1N914's.

I can't see a reason why the other one has to be a 4001 either.

Other similar noise generator circuits I've seen connect the .1uF / 100nF cap going to the noise transistor's emitter to +V not gnd....

for example:

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I would also check at the collector of the middle transistor to see if you're getting good noise there. If not, you might want to try swapping different other transistors in for the first one that should be generating the noise.

I won't pretend to be very good at transistor only circuits (I like op amps Smile

) but basically the design of the circuit is a simple noise generator going through a pseudo-vca (the third transistor etc).

PHOBoS · Posted: Fri Aug 08, 2014 5:49 am Post subject:

what's your supply voltage ?
I've never had any succes with those transistor based noise circuits with voltages <9V they usually seem to work best at 12V or higher.

Ruebezahl · Posted: Fri Aug 08, 2014 7:25 am Post subject:

Its 9V. Well maybe that could be the reason, although one commenter on youtube said, he succeeded with 9V.

@elmegil i tried the trick with connecting capacitor to +V instead of ground, but nothing changed. i also checked for noise at the, and just got this really sudden, loud noise, like when you plug in the jack in somewhere. didnt really sound like white noise, more deep, low. But it dont really know the differences between transistors and dont know what i could use instead. Do you have scematics for this kind of circuits but with op-amps?

Thanks, Rueezahl

elmegil · Posted: Fri Aug 08, 2014 8:43 am Post subject:

Several of Ray Wilson's designs on musicfromouterspace.com include noise generators. They're not "with the VCA" though.

For other possible hi hat circuits I'd look at the wiki here:

http://electro-music.com/wiki/pmwiki.php?n=Schematics.Schematics

richardc64 · Posted: Fri Aug 08, 2014 9:45 am Post subject:

The 2-transistor noise circuit absolutely works at 9V. The variations in the published schematics are mainly in the value of the cap to ground from the "first" transistor's emitter.

The op amp in my schematic shouldn't be needed when driving a 1-transistor VCA as in the Tiny Dazzler circuit.

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elmegil · Posted: Fri Aug 08, 2014 10:21 am Post subject:

It sounds to me given the description that the problem is with the 1 Transistor VCA rather than the noise circuit....

The cap going to the next stage ought to block some of the lower frequency components and make the noise "more white".

PHOBoS · Posted: Fri Aug 08, 2014 10:29 am Post subject:

Ruebezahl · Posted: Sat Aug 09, 2014 4:19 pm Post subject:

Thanks for the input. I tried the second circuit from richard. and there is no sound at all. since this part of the schematic is pretty much the same as in the original one, i really think, i am one of the persons where its not working with 9V, or maybe the transistor nowadays, are with reduced noise, and i got some of those, while the other people, who got it working, used other types (maybe being from different companys, although still being the same model). so now i have three choices.
1. get and try other transistors,
2. try it with an supply voltage of +12V (Was thinking about powering my drummachine with 12V anyway),
3. Maybe try alternative circuits with OpAmps instead of Transistors.

I think i go for the 12V Power Supply first, since i wanted to do it anyway. Lets see what happen. But i am excited, since its the first time i am gonna use a wallwart, instead of battery powered Surprised

Blue Hell · Posted: Sat Aug 09, 2014 4:37 pm Post subject:

Blue Hell · Posted: Sat Aug 09, 2014 4:52 pm Post subject:

And what Scott just mentioned in the chat ...

4. when it works on 9V and the battery goes a tad low Confused

Ruebezahl · Posted: Sat Aug 09, 2014 5:50 pm Post subject:

okay, so as soon as i can get the parts (monday) i will build a 12v power supply. One Question though: I saw that a lot of the schematics here are for +/-12V, with a virtual ground, i belive. I dont know much about that, but i would probably going for a power supply, wich is giving away +/-12V. Its compatible to circuits designed to work on a normal +12V Power Supply anyway, right? But what do I need to consider, when i have this +/- Power Supply, and a circuit wich is actually designed for a regular +12V. the point wich are connected to ground on the schematics, do i have to connect them to -12V or to 0V???

elmegil · Posted: Sat Aug 09, 2014 5:51 pm Post subject:

You could use 2 9V in series and get 18V Smile

Might want to throw a smallish regulator to bring it down to say 15V....

9V batteries don't have very good lifespan anyway though.

elmegil · Posted: Sat Aug 09, 2014 5:55 pm Post subject:

Ruebezahl · Posted: Sat Aug 09, 2014 6:11 pm Post subject:

I am gonna do the 9V in series right away, stupid that i didn't think about that Very Happy

To bring it down to 15V i just need to add a resistor after the positive pole, right? Any Suggestions for the size?

For the Power Supply: Okay that sounds like using the bipolar supply for other circuits should work just fine. So i think i will build one. Do you have any circuits, hopefully also with some explanation about setting up this kind of power supply. i cant google, since i dont know the proper word.

PS: This kind of bipolar power supply is NOT the same as alternating current, right?

elmegil · Posted: Sat Aug 09, 2014 6:35 pm Post subject:

Ruebezahl · Posted: Sat Aug 09, 2014 6:48 pm Post subject:

well i just toasted my 74HC14-Clock while trying the 18V-thing. According to the datasheet, the supply voltage shouldn't exceed 6V. But it worked just fine with 9V so far...
So in the future, if i will use the 74HC14 as a clock, i guess i have to pull down the supplyvoltage for this IC seperately...

elmegil · Posted: Sat Aug 09, 2014 7:56 pm Post subject:

-minus- · Joined: Oct 26, 2008 Posts: 761 Audio files: 13

Yes the transistor noise with the 47K and 4K7 resistors does work at 9V. I have had it working at less than 8V. You need to try different transistors of the same type and also test different types. I have had good results with 2N2222's 2N3904's and PN100's.

richardc64 · Posted: Sun Aug 10, 2014 7:13 am Post subject:

When all else fails, try a voltage doubler.