halving voltage

[amplex]

so i have a voice changer circuit i want to add to this kawasaki drum toy, but the voice changer uses 3 AAA 4.5v, vs 6 AA, 9v, what is the component that will half the DC voltage for me so I can use the same set of 6 AA's? can this be done with a resistor or do you need an IC?

[Sam_Zen]

You can use both.

One resistor is too tricky, because you probably don't know the internal impedance of the voice changer.

To get half of a DC voltage, you simply use two equal resistors in series connected to ground.
Then you can 'tap' half the voltage at the point between the two resistors.
Of course this will consume some power, so don't choose the value too low. But not too high either.
Normally a value between 10k and 33k.

To stabilise some voltage changes, it's better to add a small capacitor from that 4.5 v point to ground.

Of course, because two resistors are involved, you could replace them by a single (trim)pot using the same connections.
The target voltage will be at the middle pin of the slider.

It can be done with an IC as well, like a small version of the 7805 voltage regulator. 9 volt on the input line is just enough.
The 78xx models have 3 connections : V in - V out - ground.
Also with this, an extra el. capacitor is needed from V out to ground.
This wil produce 5 volt, but I guess the voice changer will still be functioning properly.
With things like this, the 4.5v is a compromise, because AA(A) batteries are 1.5v types

[amplex]

thanx Sam, hey another quick question, can I replace a 2n2222 with a 2n3904 for a led audio peak circuit? i know the 2n3904 switches less 'safely' but i have one here =D

the circuit im trying to make is

http://www.jnabeats.com/images/Peak%20LED%20circuit.gif


if anyone wants to check out a REALLY simple bass fuzz here is a breadboard version:

http://www.beavisaudio.com/bboard/projects/bbp_BazzFuss.pdf

[Sam_Zen]

Please one question per topic.
I don't have the specifications of the 2n3904, so you have to find out for yourself.
For switching purposes I used the 2n2222 a lot, because it's very fast.

[Lofi Ninja]

Sam_Zen.. There's no reason to make a new thread for a simple Q.. So why should't he ask ?

Switching the transistors should't be any problem..

Also Sam_Zen's soloution is pretty much over complicating it ! Just tap the 4.5 V from the 3'rd battery if they are put in a zigzag holder and not the one long tube kind. Just solder a wire to the plus side of the third battery holder and use the same ground as your 9 V. This will ofcause shorten battery life, but what wouldn't.. This wil not work if your using a wall-plug thou..

[Sam_Zen]

2 Lofi Ninja :
Simple Q or not, it's a common practice on forums to do this, to give better results if people do a search on items.
Your workaround by tapping the 4.5v from the third one in the sixpack is a nice one by the way.

[Lofi Ninja]

Oh ok... Never thought of that before..

Yes it is super easy.. I've seen it in many toys, and I've done plenty of times before.. It's sertanly better than say, using a LM78XX...

[amplex]

thanx for the help you two!!!! and i will next time post my questions in a new thread to help others searches.

its interesting that halfway down the 'battery ladder' you would get a different voltage than at the end! i always thought that since they made a connection together, that the voltage would be the same anywhere in the line, but i guess since the signal has not traveled thru the other batteries yet, it would only be half voltage (as batteries are polarized and voltage can not go the other direction thru it) .. in this lesson i think i have just learned the main mistake of wiring my WSG, which was a miswire in the zaniness/zany freq pot bridged connection to ZA1A on the board!!! (I put ZA1A to the middle leg of R13 instead of between R13 and R18 where it should be, figured it would be the same since 3 legs are bridged here anyway. Thanks a ton, will correct today, hope it works..

havent quite attacked this drum toy/machine yet, as i've been working on finishing my WSG and also helping a friend startup a local webradio station for local artists, but i had some ideas for the project, such as :

- 4 independent 555 square lfos to trigger the drums (one switch/freq pot for each pad, 4 pads, it looks like they trigger with contact mics(!) or maybe solenoids, 2 wires each pad) wish there was a way i could add a switch to do halftime/quartertime etc instead of having to dial everything in on a pot! maybe a rotary switch with some resistors that has common drum divisions like 2, 1, 1/2, 1/4, 1/8, 1/16 etc =D i know this is kind of overboard for an 8bit sounding drum toy, but its the point of glitching it into something more interesting/adding functionality IMO

- possibly a small compressor circuit, drums sound better compressed..

any ideas on a VERY simple compressor circuit (variable gain amplifier)? im thinking of using the forrest mims led flasher circuit for the lfos (and stack 4 on a piece of perfboard) located here:

http://www.mikmo.dk/555-lfo-schem.JPG

thanks again =] you guys are genius, wish i could help contribute the way you do, now would be a great time since im not working =[ sacramento area is absolutely crap for IT jobs right now.

[Sam_Zen]

If you want two 555's, there's the 556, if you want four 555's there's the 558..
Of course because of less pins, loosing some control, but not the essential ones.

[amplex]

sweet, knew about the 556 from BFDs, didnt know about 558.. i will try to work out a 558 plan for 4 lfos for my triggers, hopefully you can do 4 seperate lfos (not sure, on an 8 pin chip with at least 2 for voltage pos/neg) but even if its a subdivision triggering, that will work for a general rhythm, will work on it when im sober, thanx Sam! =]

[Lofi Ninja]

You could use hex scmitt triggers aswell.. Or quad nand gates.. 40106 and 4093 are good candidates..

[amplex]

good point, i might as well use a 40106 as i just picked up 30 on ebay =d just have to wait til they get here, the circuit should be even easier with this chip, love the simplicity of it. pos/neg and oscillators =]