The circuit is flakey. A couple of tenths of a volt margin is nothing to ship to the field.
The circuit is flakey. A couple of tenths of a volt margin is nothing to ship to the field.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
On a sunny day (Fri, 21 Mar 2014 17:08:42 +0100) it happened Cursitor Doom wrote in :
Not exactly, ONE PIC DOES ALL.
you could HEAR that nuke?
On a sunny day (Fri, 21 Mar 2014 17:11:01 +0100) it happened Cursitor Doom wrote in :
So?
in o----->|-----o---o--------o out 1n4148 | | .-. | | | --- 10k | | --- 100n '-' | | | === === GND GND
This should stretch brief clicks nicely, without needing any of that hifalutin integrated circuit crap.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
I don't have a PIC to hand and neither do I care to re-learn PIC programming for what should be a simple fix!!!
Didn't buy this thing for nucular war; just for checking canned seafood.
For what it's worth, I have surface mount Schottkeys here that measure 80mV forward voltage. Quite leaky in the reverse, if that matters.
On a sunny day (Fri, 21 Mar 2014 17:41:52 +0100) it happened Cursitor Doom wrote in :
If it shines in the dark stay clear of it! Photocell?
Computer says no. Simulation suggests this will just tail the pulses off. They might be a bit thicker at the 'base' as it were, but for this to work it would still have to be fed into a Schmitt or something similar.
[snip]
Don't you have some sort of current source driving the zener, rather than a voltage source?
Is the zener just for protection?
It would appear that Panteltje is on the right track. Just protect that NPN and then drive your logic. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
No, he's getting hungry.
Describe your pulses. I presume they are currents? ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
I'm just trying to represent the waveform I see on my analog storage scope as closely as possible that LTspice will allow. The real-world pulses the GC generates for the earpiece socket are not very uniform. They're *very* thin and spikey; too fast for a moving coil speaker to react to, I would guess. Plus they vary in amplitude from a few volts to over a dozen.
That's the principal purpose for it, yes. It might not be necessary, but I thought it best to try to protect the Schmitt input.
I'll take a closer look at what he's suggested in that respect.
Please see Message-ID: for a description.
It's worked well for me in the past, to solve a similar problem.
I didn't use a computer to fool me into thinking it'd work or not -- I actually built it and tried it out. That must have been my mistake.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
You say "volts". Source impedance or how measured?
Maximum observed voltage, minimum voltage you want detected?
Rough idea of pulse width, repetition rate? ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
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I have several little flashlights that use a single AA cell to drive a wh ite LED. There's a voltage upconverter between the cell and the LED that's the same diameter as the cell, and about 1/4 inch long. Cost, under US$1.00 each. I bought several of them just to scavenge the upconverter out of for other purposes because I can't buy/design anything better that small.
Mark L. Fergerson
Your simulation does not match any real component: The gates output only 1.0 V signal, which is not too good for the next stages.
-- -T.
How long is a string?
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Yes, I know, which is why I stated more than once that I'm posting these as schematics only and not for simulation purposes!
Indeed! It's next to impossible for me to measure, Jim. I can't display the pulses at all on my conventional scopes; I've had to resort to an old analog storage job (bw 18Mhz!) for the purpose and it's really not capable of fully resolving these pulses, which are extremely short-lived and resemble transient spikes more than a 'pulse' as such. I'm well aware that it's a very unsatisfactory state of affairs not knowing the full characterists of the signal I'm dealing with, but there's not a lot I can do about it. I have recently acquired a fancy 100Mhz digital storage scope but the controls are totally unfamiliar and I have yet to get to grips with it so that's not a lot of use either at present...
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