Digital potmeter with on/off switch?

Hello Folks,

Is there any device that can not only perform digital potmeter action with up/down rubber buttons but also replace the power switch? Ideally suitable up to 20V, automotive or so. However, that 20V could possibly be done via some regulator.

I am looking into replacing a switch/potmeter combo. It is 1M but lower values are ok. Main thing is that the whole setup does not consume more than a few uA in the switched off state.

I know that all this can be accomplished with a uC but this is meant for a quick demo.

Regards, Joerg

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Joerg
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I would suggest simply not doing this; the cost of a pot/switch is only a few dollars and may be the best solution.

Luhan (low tech) Monat

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Luhan

Hello Luhan,

Well, I wouldn't either. But this is just for a demo, along the lines of "This is how it would look and feel to a user if...". The real solution will, of course, be done with a low end uC. Sans crystal, bare bones.

Potmeters are notorious for failures. In most gear they are the number one items when it comes to QC end test failures or field failures.

:-)

I am a penny pincher myself. I hope this changes when I retire so I won't go on my wife's nerves too much :-)

Regards, Joerg

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Joerg

"Joerg" schreef in bericht news:HdR0g.66292$ snipped-for-privacy@newssvr13.news.prodigy.com...

Well, all the digital potmeters I've seen had a i2c or SPI or up/dn control inputs, not suitable for direct pushbutton connections. I'm afraid you will need a small uC anyway. Maxim has plenty of choice for digital pots.

I suppose you could make a FF from two cmos nand gates, and power the uC/pot circuit from one of the outputs, to get that 'few uA when off'. The 'up' button would always set the FF. The uC can reset the FF, once the 'down' button has steered the wiper all the way down, and putting everything to sleep.

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Thanks, Frank.
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Frank Bemelman

"Joerg" schreef in bericht news:svS0g.70305$ snipped-for-privacy@newssvr21.news.prodigy.com...

It even works on our nerves sometimes ;)

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Frank Bemelman

Hello Frank,

Dallas has some that support direct button connections. They have de-bounce on board. I have no clue why AD didn't think of that with some of their digipots.

Currently there is no uC, it's just for a few demo models. I am afraid I'll have to cook up some logic like usual. I wonder why there is no product for the typical scenario: Dormant upon power-up, wiper at bottom and not in the middle like most of them. Hit UP button, unit turns on or a logic output goes high. Hit UP some more and pot wiper goes upwards. All that's needed would be a logic output, the rest could be done with FETs and stuff. Holding the DOWN button long enough would turn it all off again.

Regards, Joerg

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Joerg

"Joerg" schreef in bericht news:pHS0g.70312$ snipped-for-privacy@newssvr21.news.prodigy.com...

Yes, I see the DS1809 now, that looks okay. Add a 4538 kludge and you're all done.

BTW, the typical scenario is that users search for an on/off switch. They panic when they can't find such button ;)

The old potmeter + switch worked, because it also gives the audible click when turned CCW.

Oh, please add the little speaker that plays "tingel di dum" when powered on, and "ta di da dom" when powered off ;)

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Thanks, Frank.
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Reply to
Frank Bemelman

Hello Frank,

It'll still be pretty messy and the pot must start at wiper bottom. Most of these need 5V or some other logic supply which this circuit doesn't have unless I add some more parts. But I guess this digipot/logic combo is the only way.

Just add ON and OFF to the + and - symbols. Or one of those pictograms that nobody understands ;-)

And offer the capability to download ringtones. For a fee, of course. Just got a cell phone. It came with six tones, all of them some weird music stuff and all IMHO pretty disgusting. I guess kids would like this metallica stuff. They don't even offer a simple beep in there. Arrrgh.

If at least they had that old Radio Noordzee jingle or the one from Wolfman Jack.

Regards, Joerg

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Joerg

Joerg, if I'm not mistaken a DalSemi digipot can - but does not necessarily - remember its setting through a power down/up. Whether wiper posn is saved or not is decided by the implementer (you, in this case). I think this is the case; it's been forever since I read the datasheet.

I think digipots are cool .... for certain applications. Not for others. I hated the radio that came with my 1986 Saab because it had no knobs at all. The day after I took delivery, on a trip from NY to Virginia, I found myself playing dodge-em with evening rush-hour traffic around Washington D.C. while simultaneously drilling through the ^%$%#! radio menus to get to the treble/bass controls! The day after I returned home I ripped that sucker out and dropped it on the dealer's desk.

Reply to
Michael

If it's just a demo, how important is it to _really_ keep the "off" current less that a uA, or can you just _tell_ them that it is? (or will be, of course). Are they going to be measuring it? After all, it's trivial to implement power-down with a micro, so you'll include that in the vinal version anyway, right? ;-)

But running a counter up and down with buttons is so trivial - couldn't you dash off a uP program in an hour or so? :-) i.e., use a micro for the demo?

Good Luck! Rich

Reply to
Rich Grise

I'd like to track down a .wav of that unique "ring" tone they used for the red hot-line phone in "Our Man Flint". Or maybe it was "Dr. Strangelove". ?:-/

Cheers! Rich

Reply to
Rich Grise

Hello Rich,

It is very important. They might take a few with them, leave them on the shelf for a week and then take them somewhere else. If the battery is flat by then it would be a major embarrassment. Remember that most of those feasibility study products will be in the hands of non-EEs. Whatever you do with feasibility studies you've got to come as close to the 'real thing' as you can. I am almost there now.

Sure, a little MSP430 can do it. But the client that has to show it needs to be able to play with all the parameters. I can't make them load the whole IAR Suite, learn how to fiddle with C or assembler source code and compile and how to rig up the JTAG or serial download. At least not within a couple of days since they've got other pressing items to tend to. Nothing beats the ease of swapping a resistor to adjust some timing. Takes 30 seconds tops.

Regards, Joerg

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Joerg

Hello Michael,

The

playing

treble/bass

it

It's not just the radios. I just had a rental car in Phoenix, Toyota Corolla, same car that my wife is driving except that it was much younger or 'new and improved'. When I hop into my wife's car I reach for the rear view and adjust it to my height within two seconds. This one had an electrified version. I guess that is called progress. Luckily the person who had the car before me must have been the same height (or gave up trying to adjust it...). It seemed not to be controlled via the usual arrow thingie to the left of the steering wheel. That would have been too simple, wouldn't it?

Regards, Joerg

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Joerg

The

playing

treble/bass

it

You mean you couldn't figure out how to program it ?:-)

I love that sort of thing. My wife opens the door on the Q45 and presses "1" and the seat and mirrors move to her position, except the seat is pushed back until she sits down and inserts the key, then it moves forward.

I'm secondary in command, so I press "2" ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Hello Jim,

Oh, I could have. But when you arrive at 9:00pm and want to meet someone at a hotel shortly thereafter there ain't much time to crack out the manuals in the glove compartment. Plus it's dark.

Alamo at PHX was interesting. You aren't assigned a car in a particular stall but they point you to a group of cars and tell you "Pick one of these". And your main roads are indeed in better shape than the ones out here. No pothole dodging. Neighborhoods seem as mixed as here. Filling up at a gas station on Dobson near 202 my credit card was rejected. The same one I used to pay at the hotel without a hitch. "See attendant...". Kind of embarrassing since I had two high-level managers with me in the car. Turns out the station didn't take cards from out-of-staters.

This can be dangerous if kids are in the car.

Regards, Joerg

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Joerg

I know, I was just razzing you ;-) Had a similar problem with a big-ass Ford SUV last year in Boston.

I've noticed that a number of car rental places are doing that now.

That's odd. Was it a national card or on a local bank? In my recent trip to southern California I had no problems. But years ago I did have problems in Boston with a card from a little Arizona one-of-a-kind neighborhood bank.

If kids are in the car they're belted up prior to my/her entrance into the driver's seat. Plus the "Q" has ample foot-room even with the seat all the way back... it's not a "toy" car after all ;-)

(And I have the kiddie locks set.)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Jim Thompson

Hello Jim,

Biggest bank there is. I was puzzled. Possibly they put card readers in the pumps and then the neighborhood crime rate became too high? The area looked ok to me. Anyway, the attendant said "Oh no, here you have to pre-pay". So I left a bill inside and then went back to retrieve the balance. The only other times I have seen that were in Oakland (CA) and in Queens (NY). Areas that I'd never visit at night.

Regards, Joerg

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Joerg

The

playing

treble/bass

dropped it

Gruess Gott, Joerg

Electric rearview mirrors? What's this world coming to?! I've seen electric

*side* mirrors (sehr gut when weather is sleeting) but not rearview. I guess the "improvements" are getting harder and harder to dream up, now that cup holders, individual DVD monitors, zoned climate controls, and-on-and-on are (probably) standard equipment. Oh! ... and rear-facing video camera; gotta have *that* (not). I'm not much on cars - I walk or bicycle - so I wouldn't be surprised if there are even more ridiculous gotta-haves in today's cars.

The Saab radio I wrote about was a Clarion. Great sound, lousy usability, but with two super features that were sorely missed when I got rid of it: auto scan tuning; multiple sets of both AM and FM station memories. Happily, fifteen years later I got a Radio Shack "headset" with those features, on close-out for just $25.

--
Michael
Reply to
Michael

Dobson/Loop 202 is no garden spot, but I wouldn't think high crime either. Probably their data link was down.

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Hello Jim,

Maybe but it trundled a while, then asked me for the zip code (that request must have come via the link). They do this back east, too, but then the pump opens up.

What surprised me was the instant answer "you can't use that here, got to pre-pay".

Regards, Joerg

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Joerg

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