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Max The Magnificent
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Re: Sorry to have missed it
Max The Magnificent   8/21/2014 9:39:27 AM
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@Rcurl: I was soooo disappointed to have missed the Hamfest this year- although it sounds like you made off with all of the choice stuff before I could have gotten there anyway.

I wish you coudl have been there with me -- both ouf us sporting our Hawaiian shirts (truth to tell, there were actually quite a few folks with Hawaiian shirts there ... but mine was the best LOL). Wait till you see my photos -- there were three vendors selling meters -- more meters than you can possibly believe -- I really only got a relatively small number compared to all the ones that were out there.

Max The Magnificent
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Re: Analog meters
Max The Magnificent   8/21/2014 9:36:45 AM
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@Rcurl: I don't think it will be difficult at all to drive a zero-center meter from a single power supply, though.

Two obvious techniques come to mind.

#1 Start with a PWM output so you can control the magnitude -- then add a dual pole dual throw relay so you can select the polarity to be applied to the meter.

#2 Like #1 but use an H-bridge type arrangement.

Max The Magnificent
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Re: Analog meters
Max The Magnificent   8/21/2014 9:34:13 AM
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@Rcurl: To go along with it, maybe synthesize a "tick" when it flicks left and a "tock" when it flicks right.

Again, using a microcontroller's PWM output, you can make a regular meter look/behave like a center-zero meter.

Max The Magnificent
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Re: Tick..Tock Sound
Max The Magnificent   8/21/2014 9:28:24 AM
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@Steve: The sound selection for the tick..tock would depend on the responsiveness of the selected meter.

I'm starting to think that I could do a follow-up blog devoted to the various sound effects one might employ... hmmm...

Crusty1
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CEO
What no Sun Dial
Crusty1   8/21/2014 5:24:02 AM
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Hi Max, My first boss at London Underground Research Labaoratory made a clock with meters for telling the time. I think it was all run with TTL 74 series IC's on veroboard.

However I think you are missing one dial which of course has to be a sun dial.

How cool to have a sun dial that works at night. Not sure how it would be achieved obviously the gnomon and dial are easy, but casting the shadow would require a led light source and stepper motor? Or would you use a fixed light source and turn the dial?

I think this might just end up on my whacky to do list.

Great article and look forward to further updates.

 

 

HeyJoe0
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Timeofdayometer
HeyJoe0   8/20/2014 10:02:39 PM
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I built an analog timeofdayometer. See picture below. Accuracy was a bigger issue than I originally imagined due to the following. I was using a long-throw movement, which have a not so constant-force springs. I tried to copy the non-linear scale of the original faceplate but that was a challange to layout (I used AutoCAD) and I never really got it right. On my next iteration Im going to use a linear scale and apply a nonlinear correction factor on my output value. Another issue was that, although I used a 32.768KHz xtal timebase, my time would drift. I used buttons in the back to set the time but next time I'm just going to throw in a GPS to get the time and forgo buttons and solve the drift problem at the same time. I tried the flicker thing and it looks cool. I only flickered the needle every 15s so it wasn't annoying.

Timeometer3

 

 

 

Wnderer
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CEO
Vintage Time Delay Relay
Wnderer   8/20/2014 8:03:18 PM
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You could make your clock seem more 'authentic' with a vintage time delay relay like this one.



 

They way I understand it you apply 6 volts to the heater and after 60 seconds the relay closes and disconnects the heater which cools down. The heater then reconnects and starts the process all over again. Your time measurement would then be retro too and you'd have a neat vacuum tube to show off. Of course it would only tick every minute instead of every second.

David Ashton
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Re: Vetinari clock
David Ashton   8/20/2014 7:14:34 PM
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@Rick...your comment got me thinking, so I googled it:

"In the excellent Discworld series the character Lord Vetinari has a clock in his waiting room which is designed to tick irregularly in order to make his visitor feel ill at ease."

So Max, is yours going to tick irregularly?  

Duane Benson
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Re: Very nice!
Duane Benson   8/20/2014 6:46:31 PM
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Have a few of these meters, but probably not enough for a clock. I do need to come up with a creative office clock though.

Max The Magnificent
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Re: I like it
Max The Magnificent   8/20/2014 6:17:33 PM
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@DIDEFIXIT: Think retrograde Very cool idea meters they count up and snap back. The sound needs to be like a water clock

Oooh -- I like both of these ideas!!!!

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