Heart beat generator for recovering patient

Thread Starter

ardorban

Joined Jan 14, 2014
10
This is a very interesting and potentially enormously helpful project for a small girl who is in recovery from a heart condition due to a virus. What has been advised would help is a small device that can be put into a soft toy that will actually beat a like a heart at chosen frequencies.

I am a beginner at this but could solder a circuit together if someone could help.

So I imagine an oscillator that then would feed some sort of vibration device - it needs to pulse/ vibrate/ beat - rather than just be an audio frequency - so not sure what this is. But all help and suggestions gratefully received.
:):)
 

t06afre

Joined May 11, 2009
5,934
Hmm sceptic about the healing part in this:rolleyes: But as it is totally non invasive it will not hurt anyone at all. What kind sound are you looking for? Will it be correct to assume some sort of slow drum beat generator. Then the a doctor listen to your heart the sound is something like this https://www.youtube.com/watch?v=8lzh9kgnoaU
 

Wendy

Joined Mar 24, 2008
21,906
There are boards that will record sounds for playback, though I'm not familiar with any firsthand. Record heart beat and put it into a loop.
 

Thread Starter

ardorban

Joined Jan 14, 2014
10
There are toys out there but they are not what is needed. Also it is not a matter of playing back an audio recording of a heart beat.

I have done some more searching and need something like the vibrator in a mobile phone.

What I need is something like a variable oscillator that drives a vibration motor, like haptic feedback to a variable rate. Is that something you guys could help with. Believe me some senior heart surgeons gave suggested this would be helpful therapeutically.
Thank you.
 

sirch2

Joined Jan 21, 2013
1,026
Not played with one for a long time but IIRC a piezo disk sounder will make a "click" when a voltage is applied, may be better than a buzzer. You may need a few to be felt through a soft toy.
 

Alec_t

Joined Sep 17, 2013
10,458
I have done some more searching and need something like the vibrator in a mobile phone.
That's what I would have suggested. Could be salvaged from a junk phone (or purchased). A simple timer circuit could easily drive it with brief pulses repeated at a typical heart rate.
 

Alec_t

Joined Sep 17, 2013
10,458
A '555' astable circuit is probably simplest. What space do you have available in the toy to accommodate batteries?
 

Thread Starter

ardorban

Joined Jan 14, 2014
10
A '555' astable circuit is probably simplest. What space do you have available in the toy to accommodate batteries?
Thank you for replying - plenty of space in toy - I thought a 555 based circuit that could drive a linear resonant vibration actuator such as the following would be perfect if you could suggest a suitable circuit with a a variable frequency that would be brilliant.

http://www.precisionmicrodrives.com/...bration-motors
 

elec_mech

Joined Nov 12, 2008
1,500
The motor you linked to requires a sine wave to drive it. A 555 typically outputs a square wave. This post has some useful information on the subject of getting a close sine wave out of a 555. This site appears to have a circuit with a variable frequency using 741 op-amps.

I don't quite see how a vibration motor will truly mimic a heartbeat, but don't let me stifle your creativity. :)

I know you said you don't (only) want an audio circuit, but another thought is adding an amplifier to a playback module or metronome designed to increase the bass. Bass is often more "felt" than heard. This is where I would start if it were me.
 

tracecom

Joined Apr 16, 2010
3,944
I think I would try a small solenoid controlled by a 555 or similar timer circuit. The solenoid could be allowed to strike a sound board enclosed in padding to muffle the high frequencies, and accentuate the bass. I don't have the mechanical specifics in mind, but some experimentation should produce an acceptable sound. Perhaps the solenoid could even be arranged to make a sound on the push stroke and a lesser sound on the return stroke, thus emulating the lub-dub of a heartbeat.
 

Thread Starter

ardorban

Joined Jan 14, 2014
10
I know you said you don't (only) want an audio circuit, but another thought is adding an amplifier to a playback module or metronome designed to increase the bass. Bass is often more "felt" than heard. This is where I would start if it were me.[/QUOTE]

That sounds a good idea also, will try and make both and see which she prefers. Could you possibly suggest an adapted metronome circuit that would give a high bass amplitude. I really am a beginner and need the whole circuit please....!

Thank you
 

Alec_t

Joined Sep 17, 2013
10,458
The link you posted is suspicious. I don't trust the '404 error' banner at the top of its web-page, so I won't click anywhere on that page.
If you were trying to link to a linear vibrator for haptic feedback, have you noted the 1-off price? Seems expensive. Worth first trying a cheap standard headphone/earbud ? That could be made to give clicks which, when muffled, might pass for heartbeat sounds.

A couple of years ago my granddaughter went to a 'make-a-bear' party, where soft toy bears had optional accessories inserted, including a heartbeat unit. Might be worth searching for that.

Edit: Here's a link to bear voice-boxes. Given the prices shown, it's hardly worth making your own.
http://www.bearfactoryparties.co.uk/teddy-bear-accessories/teddy-bear-voice-boxes-50-c.html
 
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tracecom

Joined Apr 16, 2010
3,944
Could you possibly suggest an adapted metronome circuit that would give a high bass amplitude. I really am a beginner and need the whole circuit please....!

Thank you
Here is a metronome type circuit that runs at about 1Hz. The power supply is shown as 12V, but it will run fine down to 5V. The speaker impedance is 8Ω. To be honest, it sounds more like a clock ticking than a heartbeat, but maybe it will get you started.

ETA: I just noticed that the switch is wrong, but I don't want to redraw the schematic. Leave out the switch that I drew and R3. Connect pin 4 to pin 8, and put a simple on/off switch between the +V supply and the rest of the circuit.
 

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