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Please tell me how you would design. Application - Operate vibrating motor with 1 button battery and on/off swith. The PRIMARY desgn concern is SMALL in size - every MM is critical. Battery should operate motor for 15-30 mintues at full power - we don't want to regulate power to motor as the battery is barely enough to drive it as is.

Operation - Initiate on button (assume tact switch) motor runs and remains running until switch is initiated again and motor is now off.

Planned components.

Battery - LR43/G10 -

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(smallest battery we can effectively use as far I know) OTHER OPTION 2 G8 batteries get's us to 3Vs

Motor -

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OPTION 2 with 2GB batteries 3V -
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Switch -

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I have assumed a tact switch because I could not find a latching mechanical switch that was small in size. A latching switch would be nice because that simplifies things. The other MUST on the switch is low operting force - would prefer 160Gf or less. Once again SIZE is critical - I would like to keep it below 6x4x5 (LxWxH) mm.

So if we use a tact switch then we need an IC switch of some sort. Press then release the tact sw., circuit is closed and motor operates (circuit remains closed). Press then release tact sw. again and motor is now off/circuit open. This is the part that is missing some sort of switching IC. I am working with a factory in China and they had a concern that as the voltage drops off the IC will not work properly. This might be the low dropout? I am no electrical enginner, but I do search hard and I noticed a lot of the IC switches that I researched require 1.65V or more to operate. I'm not even sure I'm looking at the correct components, but I can imagine a switch requires some V to remain in the closed/latched position. I think the concern is the motor sucks a lot of power from the battery and V will drop off - but we want the motor to operate at the highest capacity until the battery is dead or it is turned off.

I had one response earlier that suggested a NPN transistor, but I am wondering if this works with the tact switch - circuit remains closed after momentary intitiation of tact switch. Please excuse my ignorance, but I'm trying to understand and learn.

Please remember SIZE is extremely important. You can call me if you have any questions 480-990-3023.

Thanks for looking at this and responding.

Some guy asked if I would pay through PayPal - I'm not opposed to this if you are sure you can do what I need within the space constraints; however, I really didn' think this was rocket science.

Randy

Reply to
rmartin929
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This is a doable thing.

You are probably correct in that an IC won't cut it, at least on one battery. You need a circuit that will stay with you down to a supply voltage of 0.9V or so. While one transistor won't do it, a pair of transistors will give you the 'latch on' part, and will be pretty small with surface mount components. There's probably a way to get the 'and turn off' part, too, possibly even in a small circuit.

If you are getting enough of these made you may want to consider seeing if you can get the motor in a custom wind, for 2.8 or 2.6V. The extra battery will give you lots of extra head room, but the 2V motor will suck current pretty fast from a pair of fully charged batteries -- some experimentation would let you know if this is going to work, though.

If you are _really_ getting enough of these made, and they really have to be small (10K to 100K quantities), you may want to talk to someone who does custom chips. I'd see if it could be done with discretes, first, to prove out the circuit idea as well as the marketing concept.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Reply to
Tim Wescott

Use an existing tiny slide switch, or design one into the housing. Electronics will cost more, take more space, and waste battery energy.

John

Reply to
John Larkin

True. Unless you are in love with the pushbutton idea. I was thinking of what I'd seen in the Digi-Key catalog, not what I've seen on toys imported from China.

But it'd be a fun circuit to build, so if you love the pushbutton idea, give one of us a call!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Reply to
Tim Wescott

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Is this application for a "single girls best friend?" Sounds like what you want is a ball point pen type switch. Push once for on push again for off.

Reply to
Bob Eld

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