Potato sprinkle recording

[Harry Dalek]

From the last subject post i was inspired and thinking how could i do an audio recording with junk , free styling like most thinkings i try to put together i just see how it gos try and change if it doesn't work or you come up with a new idea .
I want small ...i want accurate....as for mechanical recording Thomas Edison style i am tossing this up thinking more of a drum magnetic recorder I like the first magnetic recording device the wire recorder the wire is wrapped around the drum which i suppose is the recording tracks ..telegraphone

Anyway stepper motor for the drum do away with the screw and get the speed correct

see how i go on the head movement .

[Harry Dalek]

Worked out the basics .
i would like a stepper to do the head movement depends how slow i can move the head gear dc motor and accurate with pulses ,so worth keeping that motor if so.

[Steve Anderson]

Hi Harry, if you wanna have a bash at wire recording I have uploaded a book into the 'Resources' section of this forum under the thread "Tape and Wire audio recording". It should help you with some of the pitfalls to be avoided. It's from 1952 by M.L.Quartermaine entitled, "Magnetic recording, wire & tape".

Being that old the generic circuits are all tube/valve based but should be translatable into semiconductor use.

I'm a bit wary at your use of a stepper-motor though, it could give you a severe dose of the 'flutters', as in wow & flutter from record turntables. I guess it depends on the step size and speed. Some inertia may help.

One suggestion is to not feed the motor with quadrature square-waves but quadrature sine waves, this should smooth things out at the expense of a bit more complexity...and heat dissipation.

Don't forget to have your Four and Sixpence ready (front cover).

Steve A.

You might want to confer with Albert r.e. his Edikow machine and the mechanical headaches involved.

[gary]

One suggestion is to not feed the motor with quadrature square-waves but quadrature sine waves, this should smooth things out at the expense of a bit more complexity...and heat dissipation.

Spot on! However in this case it may be extremely simple to drive them with sine waves - what rotational speed will you using?

A transformer and a capacitor is all you need to drive a stepper at the following speed:

rpm = 2 x mains freq x step angle / 3

In fact you don't even need the transformer but for safety's sake it is highly recommended.

Of course it would be at the mercy of mains frequency fluctuations but so are many record players.

OTOH Steve, if you turned your mighty talents to developing a suitable (read simple and inexpensive) push-pull amplifier driver it would have many applications in NBTV - cheap synchronous motors for all!

[Steve Anderson]

OTOH Steve, if you turned your mighty talents to developing a suitable (read simple and inexpensive) push-pull amplifier driver it would have many applications in NBTV - cheap synchronous motors for all!

For smaller steppers (up to several watts) a pair of TDA2030s or TDA2040s are about as simple a power sine-driver as you'd ever need. They're basically power op-amps and if you heed the advice in the datasheet thery're as simple to use as ordinary op-amps...don't forget the heatsink though!

They can be configured for single-supply or split as you require.

Beyond that there are many others, up to and over 100W, it all depends on what you can get locally. I have attached a few sample datasheets...they're all made by many companies, TI, STM, National, Philips and so on...all generally stocked by the usual suppliers...

As far as the chip is concerned a stepper motor is really not much different to a loudspeaker, it's a mish-mash of resistance, capacitance and inductance. It takes a really awkward load to make these things unstable.

Steve A.

[gary]

Ah that's the easy way out. Actually the problem there is that you need a dual power supply to avoid whopping big caps or a transformer on the output.

I have used various configurations in the past and they all work but have never quite been able to come up with something that is both cheap and simple which I feel is a requisite for NBTV. Generally speaking you end up with the last and second last stage of a power audio amplifier which costs a good fraction of an of the shelf unit.

Of course I was looking at heftier steppers than Harry probably needs for this project, perhaps it needs someone to look at it from a different angle.

[Harry Dalek]

Hi Steve

Hi Harry, if you wanna have a bash at wire recording I have uploaded a book into the 'Resources' section of this forum under the thread "Tape and Wire audio recording". It should help you with some of the pitfalls to be avoided. It's from 1952 by M.L.Quartermaine entitled, "Magnetic recording, wire & tape".

Thanks Steve i will download for sure its some thing i have never had a go at i like the wire idea.

Being that old the generic circuits are all tube/valve based but should be translatable into semiconductor use.

Thats ok i think the speed record head and such is something i need to look into more than the electronics

I'm a bit wary at your use of a stepper-motor though, it could give you a severe dose of the 'flutters', as in wow & flutter from record turntables. I guess it depends on the step size and speed. Some inertia may help.

I think yes if i push it and try to slow for more record time but interesting to find out

One suggestion is to not feed the motor with quadrature square-waves but quadrature sine waves, this should smooth things out at the expense of a bit more complexity...and heat dissipation.

This is something i have not tried at all reading it sounds a bit beyond me at this time ,i have to read up on it a bit more .

Don't forget to have your Four and Sixpence ready (front cover).

[/quote]

No worries Steve

BTW the Japanese have the best toys !

http://otonanokagaku.net/english/magazi ... index.html

[Steve Anderson]

Ah that's the easy way out. Actually the problem there is that you need a dual power supply to avoid whopping big caps or a transformer on the output.

Well, consider this....single supply you'll need a big reservoir capacitor of a certain voltage, then two more on each quadrature power sine-driver output, a total of three.

Split-supply you'll need two reservoir capacitors of lesser voltage, but no output caps...a slam-dunk to me...

...and you've still got +/- for the rest of the gubbins...if needed.

One of several reasons I prefer split-supplies

Whichever way you look at it you're gonna need at least two large(ish) caps however you do it...still only a single bridge rectumfrier...OK, the transformer secondary needs a centre-tap...shouldn't be a hassle...Watts = large caps...

Steve A.

[gary]

In principle yes, no doubt about it, in practice it's a problem because few "salvaged" transformers have the required tap.

BTW what the hell IS a slam-dunk??


There are ways around it that I was investigating before life events overtook me, but what is needed is a kind of H-Bridge power amplifier - should be possible.

[Steve Anderson]

but what is needed is a kind of H-Bridge power amplifier - should be possible.

Yes, called a BTL amplifier (Brigded-TransformerLess) these are extensively used in car audio to get at least a moderate amount power out of an amplifier running on only 12V. There are chips tailored for this application. From the small 1W/6V TDA7052 to the 20W/12V TDA2005. The load impedances are generally very low though, 4 or even 2 Ohms.

If the steppers windings fit into this scheme then it is possible...

Steve A.

Slam-dunk? Slam the loo door and shove your opponents head down the pan? I dunno.

[gary]

Ah yes, I remember now... that was the last thing I was looking at when I was somewhat distracted... hmmm I may have even ordered something.

Damn it's annoying that I probably won't be able to get back to NBTV this year, so many things to do, so little time...

BTW to my great shame and annoyance I keep ordering things, parts, components, and never get the opportunity to implement something, it's very frustrating.

But I still see the use of steppers as synchronous motors as a great opportunity for NBTV. Definitely worth persevering with and surprisingly little has been done in that area.

[Steve Anderson]

But I still see the use of steppers as synchronous motors as a great opportunity for NBTV. Definitely worth persevering with and surprisingly little has been done in that area.

It's one of many things I have on my "To Do" list, but like yourself many things conspire against me. I have a printer that is nearing cessation, I hate to think of it as a future cadaver for dismemberment, but soon it will become so. I view it's internals with interest but I guess I should take some measurements on paper speed etc,., then calculate gear ratios to find out the normal rotation shaft speed of various steppers within...

Oh well, one day...

Steve A.

[Harry Dalek]

I am using a unipolar seems to have very fine steppers turning it but thinking about the problem if it comes about i do have a geared dc or 2 handy .

Looking at wire recorders i came across this loop wire recorder home made record playback head .

I have been toying with the idea of using a hall effect sensor as the play back head but i do like the dual simple one in that photo.

Looking at the first recorder i think that the wire wrapped around the drum is just there so the grooves of the wire screw is there to move walk the head or you would just use a tin or steel drum .

So i am thinking about should i use steel wire ...or paste rust to it ..wrap it in magnetic tape swap it for a small tin can ...what i am not sure about is can you write tracks to a say a Can then i am thinking is it any different to wire thats butted up to each other.

[gary]

In reference to what Steve and I have been saying the following circuit is all you would need for the speed calculation I have given.

[Harry Dalek]

In reference to what Steve and I have been saying the following circuit is all you would need for the speed calculation I have given.

Hi Gary i am using a 5 pin unipolar that looks like a 4 or 6 pin bipolar ,i do have a few of those about as well....have to say that is a simple circuit saves a lot of electronics .

Does it just work off 12volts bet the stepper gets hot ?

What governs the speed Gary the line frequency could you use say instead of just line Ac transformer a 555 timer at that frequency feeding a mosfet perhaps also turning that square wave to a sine wave before the trany sounds like a simple way to get speed control out of a stepper?