Newbie question: EMDR project

No idea how to proceed with making what is likely a pretty simple device, but I have *no* background in electronics. OK, here is what I want:

Two handheld cell-phone style vibrators that "take turns" vibrating, each connected to a central control device which allows changing the speed of the switching back and forth.

As a bonus, but not needed, it would be good to have a way to connect headphones which would be able to play some sound that is timed to the same back-and-forth behavior: when the left "vibrator" (is there a better word!) is active, a sound is played for the left ear; same thing for the right.

I suspect for someone who has a clue this is not that hard to make... but for me: completely out of my league. Any ideas? Wrong group?

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Snit
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Right group. How many do you want to build?

In spite of the ire recently directed toward it in s.e.d, this is an ideal sort of application for a 555 timer chip (or a small microprocessor).

One 555 set up to toggle with a 50% duty cycle, with a potentiometer to vary the frequency. NPN (or MOSFET) pulldowns to the vibrator motors. One or two more to drive sound to the headphones, if all you want is an unpleasant buzz.

Or do it all with one teeny microprocessor and some code.

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Reply to
Tim Wescott

Tim Wescott stated in post xYWdndJkyO3MaErQnZ2dnUVZ snipped-for-privacy@web-ster.com on

5/21/11 10:24 AM:

To start off with, just one.

All of that goes well over my head, but at least it gives me direction to look at and do research on. Very much appreciate it.

Hopefully a pleasant beep... best case would be a recordable sound, but if not, a pleasant beep at the very least.

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Reply to
Snit

The 555 produces a square wave, which has a similar sound to that that which PCs make in the early stages of booting,

there's a sample here.

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it's not musical, but neither is it nails on a chalkboard. (it also sounds a bit nicer down an octave to two)

a small microcontroller with PWM output could produce a much nicer sound (and also control the timing and vibrators) at the cost of increased design complexity, this will basically get you "child's toy" quality sound.

there are other ways to make sounds electronically but these are two of the cheapest.

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Reply to
Jasen Betts

"Snit" schreef in bericht news:C9FD494A.98B21% snipped-for-privacy@gallopinginsanity.com...

I'd use one PIC12F675, two transistors, two diodes, four resistors, three capacitors... and some code. But, alas that's way beyond the skills od this OP.

To stay on the most simple side, I advise to go and use some likewise simple astable multivibrators. The basic idea is drawn below.

Use a fixed (typewriter) font to see these drawings.

+----+----------+----+----6V | | | | | | | | .-. .-. .-. .-. 4k7| | | |68k 68k| | | |4k7 | | | | | | | | '-' '-' '-' '-' | | ||10n | | | +----||----)----+ | | || | | out2----+ | | +----out1 | | ||10n | | +----)----||----+ | | | || | | \| | | |/ |--+ +--| | | | | | | +--------------------+---GND created by Andy´s ASCII-Circuit v1.24.140803 Beta
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Transistors can be any type of NPN general purpose transistor. Back from the old BC108 to to the less aged BC550 or even newer ones.

As dimensioned above, I guess it's frequency is somewere around 1kHz which may do for an audible tone.

For alternativly switching the vibrators, you can use the same concept but at much lower a frequency. You can try to enlarge the 68k resistors up to 1M and the 10n capacitors up to 100uF and beyond. It all depends on the frequency you need. To make the frequency adjustable, replace a part of the base resistors by a dual potmeter.

-+----+-------- ----+------ | | | vibrator 1.-. | | ( M ) - | '-' ^ Si | | | | +----+ | | from ___ |/ | ---|___|--+---| | audio | |>

| | | out 1 ___ |/ | | ___ ||audio 1 -----|___|---| T5 | +--|___|---||---- from |> | | || out alternator | out 2 |/ .-. | -------| | | | from |> | | . | alternator| '-' | | | | | | ---------------+----- -------+-----+----------------- created by Andy´s ASCII-Circuit v1.24.140803 Beta

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To drive your vibrators and phones look at the circuits above. Be aware 1: T5 must be able to handle the (inrush!) current trough the vibrator. Be aware 2: Out 1 driver vibrator 1 and audio 2. Likewise out 2 drives vibrator 2 and audio 1.

petrus bitbyter

Reply to
petrus bitbyter

Someone needs to write a book titled "Basic electronics for folks who just want to make stuff work", backed up by text that lives up to the title. In fact, Amazon has both "Electronics for Dummies" and "The Complete Idiot's Guide to Electronics 101". The "Complete Idiot's Guide" is not coming out until July, though, and besides, the authors don't even know how to spell their last names.

If you live in the US, stop by Radio Shack and get copies of "Engineer's Mini-Notebook" Volume 1 (Timers, Op-amps, etc.), and Volume IV (Electronic fundamentals). Volume 1 will have 555 timer circuits, Volume IV will tell you how to read schematics (I hope!). Browse the books in the store, and buy enough parts to make a light blinking circuit (there'll be at least one in Volume 1). When you run into problems, or when you get to the point where you're making a pair of LED's come on when you want your vibrators to come on, check back here.

As an alternative, while you're at Radio Shack you can ask for help. Note when you read this, that a sympathetic shudder has gone through every denizen of this newsgroup who lives close to a Radio Shack. For a competent person, asking for help at Radio Shack is kind of like hauling off and giving the Tar Baby a good healthy kick.

This is because approximately 99% of all Radio Shack employees are barely competent to find their way to work in the morning, but they are obviously trained -- and regularly abjured -- to be Very Helpful. This means that if you are incautious enough to ask a question, they will latch on to you and provide you with _completely useless_ information, even after you have tried to get enough distance from them that you can study the damn shelves yourself and think.

However, the remainder are scary-competent, and often know their way around circuits (our local Rat Shack is next to a community college, so we enjoy a much higher percentage, although for some reason the competent ones are nearly always young women -- perhaps the hiring manager there is trying to keep the staff incompetent, but gets distracted by their looks). They have also been trained and abjured to be really helpful, and usually are. They never last long -- probably because when you ask them a question they answer immediately, and then probably get dinged by store management for "not taking long enough with customers".

So if you tell them what you're doing and ask for help, chances are you'll end up having your time wasted by the barrel. But if by slim chance you _do_ get concrete help, it'll be good.

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Tim Wescott

the

me

!)

Reply to
joseph

I forgot to mention -- pick up a project board (one of the white thingies with all the teeny square holes). They're both a blessing and a curse, but at your level they'll be more blessing. You'll be able to build circuits on one and test them, rapidly change component values, etc., all without soldering.

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Tim Wescott

Jasen Betts stated in post irdc11$arc$ snipped-for-privacy@reversiblemaps.ath.cx on 5/23/11

3:13 AM:

Thanks.

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Snit

petrus bitbyter stated in post

4dda6c96$0$7483$ snipped-for-privacy@dreader29.news.xs4all.nl on 5/23/11 7:18 AM:

Are you suggesting I am ignorant and have no skills in this area? Oh. If so, you are right. :)

Excellent... thanks for the info. Saved and will dig through it to see if I can understand it. :)

Realistically, you made it simple enough where I think I might be able to. Thanks.

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Snit

Tim Wescott stated in post y_mdnVUcrJwe4kfQnZ2dnUVZ snipped-for-privacy@web-ster.com on

5/23/11 8:44 AM:

Fair enough (I need to learn to fish to make the catch I want!)

I have run into that. While I am all but completely ignorant in this area, I *have* made a light sensor that could be hooked up to an old Apple IIe and did the programming (with plenty of online help) to be able to record when the light beams were broken (I was helping people measure the speed of fruit flies. Really).

LOL! Or they find better paying jobs.

Thanks... for the help and the humor. :)

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Reply to
Snit

The vibrator in a cell phone is a DC motor with an eccentric weight. If you want different 'speeds' just change the motor drive voltage (which can be done electronically) or use two motors with different speeds (this means changing the impedance of the windings).

A 'central control device' could be just about anything.

Reply to
whit3rd

whit3rd stated in post snipped-for-privacy@glegroupsg2000goo.googlegroups.com on

5/23/11 2:44 PM:

I am not looking to have the vibrations change speed - but I do not want them both vibrating at the same time. The idea is to have one on when the other is off... and then be able to change the speed that the two switch back and forth.

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Reply to
Snit

Use a 555 to set the timing (set to twice the frequency you want to switch) and a toggle flip-flop to divide that by two. Use the Q for one vibrator and the Q-Bar for the other.

Reply to
krw

snipped-for-privacy@att.bizzzzzzzzzzzz stated in post snipped-for-privacy@4ax.com on 5/23/11 5:52 PM:

While sounding vaguely dirty, that gives me some more direction. Thanks. :)

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Reply to
Snit

IIRC, whoever it was just fed the output (probably a CMOS 555 would work better) back to both the threshold and trigger, or something like that, essentially reducing the 555 to an inverter in one of those inverter oscillator arrangements.

With my luck, it was John Woodgate or somebody like that. I wonder if Spehro or either of the other Johns are following the thread; I'm almost sure it was one of those guys, or that other guy whose name I can't remember - it was some years ago.

Cheers! Rich

Reply to
Rich Grise

For some reason most 555 datasheets omit the simplest oscilator circuit: use the below, make R1 variable. ----+--- vcc | +-[R1]--------|--------+ | | | | +--------+ | | | | | | | . . . .|. . . . | | | . VCC(8) . | | | . . | | +--RES(4) OUT(3)--+--> out1 (totem pole) | . 555 . +-------TH(6) DIS(7)-----> out2 (open collector) | . . +-------TR(2) CV(5)-- C1 | . . ===== . GND(1) . | . . . .|. . . . | | +-------------+ | ---+-- gnd the frequency is approximately 0.72/(R1*C1)

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Reply to
Jasen Betts

The idea predates these newsgroups.

I saw it in "Electronics" in something like the Designer's Notebook (or the other similar feature, Something Casebook)). It even predates the CMOS 555.

It must have been around 1974. I took the circuit, left off the pullup resistor that didn't matter to me, and every time since I needed a simple square wave oscillator, I've used that. It beats fussing with two timing resistors like the standard 555 circuit requires. Yes, in some cases you want something fancier, but for a lot of uses, it doesn't matter.

The circuit has been in Walter Jung's "IC Timer Cookbook" since 1977. It references the original article, which was in "Electronics" for June

21st, 1973, S.A. Orrel wrote the bit, "IC Timer Plus Resistor Can Produce Square Waves". So obviously there was no pullup in the original, the circuit in the book doesn't show one and that blurb indicates otherwise.

Walter Jung then shows an improved circuit, that has a 1K pullup resistor from pin 3 of the 555 to the positive supply, to get rid of the assymetrical output. He doesn't credit anyone for that circuit, so he may be the originator.

Pin 3, the output of the 555, goes through a timing resistor to where pins

6 and 2 are connected in parallel, with a timing capacitor from that junction to ground.

Michael

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Michael Black

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John Fields

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It's threshold and trigger in parallel, not threshold and discharge:
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John Fields

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