Dear All,Does anyone have an idea for a lowvoltage threshold circuit that switches from its Low (Off) to High (On) state (or vice versa) upon an input voltage reaching a fixed predetermined low voltage level of .... say 0.658 volts?The design must disregard all input voltage variations (DC and/or AC) untilthe threshold ( or higher ) voltage of0.658 volts is reached and at this point,switch On and remain On until the inputvoltage drops below 0.658 volts.The output will be resistive and switchbetween zero volt and the supply voltage( about 4.5 volts to 12 volts )I think one could call the circuit a "lowvoltage threshold switch".The simpler the design and lower thecomponent count, the better.Ideas ..... anyone? ............. :-)

You've just described a comparator - the National Semiconductor LM393is simple example of the devicewhere you have connected your unknown voltage to one input and a 0.685Vreference voltage to the other.The output isn't normally described as resistive - it is the collectorof a transistor whose emitter is connected to the negative supply pinof the comparator, which is normally connected to 0V. This sort of"open collector" output is typical for cheap comparators.The somewhat more expensive LM311has a more flexible version of this output stage.There are a great many other comparators available - if you tell us abit more about what you are trying to do, we can probably be a lot morehelpful.This is a pretty elementary question, and probably should have beenposted on ----------Bill Sloman, Nijmegen

Can you help design this circuit .....

Feb 21, 2005 46 Replies

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Terry Pinnell 21 years ago

John: You used to give a Subject when referencing posts to alt.binaries.schematics.electronic. I've recently split my news reading so that all binary groups are in another 'instance' of my newsreader. (Agent is still incapable of handling multiple servers, although still my preferred email/news reader). So I can no longer simply d-click a news: reference to get to your post. It's no big deal (I can find it pretty quickly), but I'd appreciate your returning to including the Subject and maybe date please.

Terry Pinnell Hobbyist, West Sussex, UK

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John Fields 21 years ago

Sure, no problem. I don't understand why you can't just click on the URL, though, I'm also using Agent and it works for me. Version 2.0, though. Maybe that's it?

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Jim Thompson 21 years ago

Agent v3 is supposed to handle multiple servers.

...Jim Thompson

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John Fields 21 years ago

No, but I'm still at a loss to understand why, if you use your second instance of Agent to access binaries, it won't decode the link and send you to the referenced post.

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Robert Monsen 21 years ago

-- Regards, Robert Monsen

"Your Highness, I have no need of this hypothesis." - Pierre Laplace (1749-1827), to Napoleon, on why his works on celestial mechanics make no mention of God.

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Terry Pinnell 21 years ago

Thanks.

It's because alt.binaries.schematics.electronic is not in my list of newsgroups in *this* instance of Agent. The free server I use for this instance is News.Individual.Net, which is excellent but doesn't carry binary groups. When I want to work with binaries (schematics, music, pictures), I load up another instance of Agent, which uses the Forte APN server, that does cover all the binaries.

Last time I checked, Agent 2.0 still did not support multiple servers. Has that changed?

Terry Pinnell Hobbyist, West Sussex, UK

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Terry Pinnell 21 years ago

The link is in the text instance (this one, in which I'm composing this reply). Your schematic is in alt.binaries.schematics.electronic, the binaries instance. Even with both running, clicking here in this instance doesn't find any messages outside.

When I had *all* my groups in one instance, using a server that handled them all, it was fine. That was before I moved to a broadband service. I missed the small print which excluded both email and Usenet access! So had to make different arrangements.

I *could* still have all groups in one instance, and use the APN server that supports all of them. But that's a limited download monthly (5 GB), So I want to use the free one for all but binaries.

Terry Pinnell Hobbyist, West Sussex, UK

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