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10V analog strobe controller

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Jebimasta View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Topic: 10V analog strobe controller
    Posted: 16 January 2013 at 2:31pm
I've got my hands on a strobe that has the 1/4" jack input on the back for a controller.

Simply putting a 10V over that input will make the strobe flash once, I've tried a 9V battery and 6V of AA, both work.

I like little DIY projects so I was wondering if anyone knew any neat ways of making the thing actually strobe without having to bash a button. I guess choosing a rate would become pretty straight forward once I knew how it actually re-triggers.

Thanks


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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2013 at 2:36pm
If you don't mind soldering you could knock up an astable oscillator circuit with adjustable frequency or perhaps something based around a 555 timer IC. A switching FET could provide level changes to 10V if needed.

Edit - have a looky here


Edited by odc04r - 16 January 2013 at 2:38pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2013 at 2:49pm
Cool! soldering is no issue, design might be another story ;)

If I understand the summary of astable oscillators, the frequency can be changed by choosing suitable capacitors and simply using potentiometers to change the resistances? and will any old transistor do? I guess there isn't much power involved.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2013 at 3:27pm
Hmm I could even solve it to give me resistance values for some common frequencies, so I could get in sync flashing at a few key rates, 4.167Hz for twice every beat at 125bpm for example. I know I probably won't be able to achieve this accuracy but good for bursts

Might build myself a nice little box with a few pots and switches once my exams are over!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2013 at 4:36pm
I imagine more or less any small signal BJT transistor would suffice, it's only switching positive feedback after all.

Yep just by varying some resistances you can change the frequency and duty cycle of the waveform. You can get stereo ganged pots if you wish to change 2 at one time.

If you want to simulate the circuit you could try LTSPICE which is a free download. It should come with enough transistor models to get you up and running.

Depending on the input impedance of the strobe you may wish to buffer the circuit output with a couple of inverting gates or a switching FET.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2013 at 6:30pm
LTSPICE shows a big 2-4 second gap at the start of the simulation before the flip flopping starts, is this just simulation or actually what I should expect to happen? I've read that certain ways of drawing an astable vibrator in simulators work better than others.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2013 at 7:33pm
An astable vibrator will work or it won't. The gap must be the software.
Mind you, I knocked up a quick 10V strobe controller using a 555 chip. Might be worth a look.
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2013 at 3:24am
Using ICs is a whole new ballgame to me. I just read a few things, but are there calculations that can be done to predict a relatively accurate frequency with a 555 chip? 
I'm wondering what the chances are I can get resistance values accurate enough in either case to allow a 5 or so second burst in sync with a pre determined BPM. I know tolerances are typically 10% or so, but what can I realistically expect from a component? If I got a 10uf cap that was actually 11uf I wouldn't exactly be pleased.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2013 at 4:09am
Alright, here's what I've come up with Cool

120 X 170mm box with 10 arcade buttons  and one potentiometer, inspiration from the Midi Fighter controller from DJtechtools.com. Powered by batteries for now, but easy enough to add a wired connection if I fancied it. I already have some of the parts for an A stable vibrator and I managed to get one to sim quite nicely so I'm going with that.

There are 3 channels with 3 buttons each, the buttons are either 1/2/4 flashes per beat, and each channel is tuned to one of my most commonly used BPMs.

The potentiometer and extra button are  there to allow anything from 0.5-18Hz.

should get it built this week and give it a test on friday Smile

Any thoughts? extra little features I could chuck in whilst I'm at it?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2013 at 8:23pm
I think this is the first time I've used simulations and calculations to build a circuit.

I was warned about tolerances, but I was still shocked by the difference between simulated behaviour and real life behaviour.

The rates were so drastically different with the calculated resistances I couldn't actually use the resistors I had bought. note to self, simulation isn't so theory isn't so reliable.

What I ended up doing was redesigning a few things and using a potentiometer to find the right frequency and measure the pots resistance once I had got a good sync.


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