What is the smallest voltmeter?

I'm looking for the very smallest -- panel mount -- LCD voltmeter. My Google searches have been dissapointing. The smallest I could find is about 2" wide.

This will be part of a 12V bicycle light system. It will mount in a small box, probably on the handlebars. It's measurement range should be about 8 to 20 volts.

A voltmeter is not complicated. I would think that one could easily be made in a 1/2" square.

Does anyone know of a really tiny voltmeter?

Thanks for your help.

Reply to
Bruce W.1
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Here is the smallest I have used, from Digikey:

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Pretty spendy, though. You would have to scale the voltage down with a voltage divider.

Reply to
John Popelish

Well, you might be able to use LEDs of different colors, or a small seven segment LED (or LCD) to indicate one of 10 voltage levels. Add an led to the display to get 20 levels.

But without more information on your constraints and objective function, we're just playing bring me a rock.

Chuck

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Reply to
chuck

Why Must it be Digital, Any number of miniature analog meters are available Surplus ! Is there any need for anything more accurate than Low Medium and High ! All you would need is the Meter Movement, a suitable range Resistor and a tiny light bulb with perhaps a dimming resistor, for Night-time operation. A total of 4 components. If it is only to monitor the Generator Output, all you really need to do is to observe the brightness of a tiny bulb wired across the output of the generator. Perhaps a 800 ohm resistor a silicon Diode and an appropriate colored LED would be even cheaper than a light Bulb these days. You might not even need the Silicon Diode if the Reverse Voltage rating of the LED is not exceeded.

Is this to be used to monitor the Lighting System on a Bicycle ? To explain why the Headlight/Tail-lights are not working ? Spend the money on a Multi Ultra Bright White LED headlight and a Multi LED tail-light instead of a Voltmeter, and then, only a broken wire or no output from the generator would result in no light output. The age of the electric light bulb and broken filaments has now ended.

Yukio YANO

Reply to
Yukio YANO

bicycle vibration destroys many things. beware. environment is a problem, dust/moisture will rot electronics faster than u can imagine!

solid state better, LCD no good in cold temps, LED consumes more power than LCD

simple bar LED circuit best for utility purposes. many avail. many circuits avail.

if you want numeric volt readings for ego sake, use a cheap multimeter from Sears or ebay (less than $10). small and durable.

Reply to
<hapticz

Cheap and tiny, but requiring a bit of cobbling: Get a cheap DMM (often on sale at Harbor Freight for under $5). These have displays about 1/2" high and 2" long. (Hey. you have to be able to read the display! half-inch square would be tought unless you had really tiny digits..) Inside the case is a big rotary range selector switch and a little chip under a black blob. Just figure out which connections are made for the range you want, hot-wire those and eliminate the switch, and install in the smaller case of your choice.

Oh, the DMMs run on 9V, but they don't draw much juice so you can probably drop the 12V with a simple zener circuit.

Best regards,

Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis

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Reply to
Bob Masta

Definitely inexpensive.

Some (many) DM's can't measure their own battery supply - something the op may run into with the meter he chooses.

The problem can be solved with some diodes to shift the ground reference, but that may make it necessary to change the voltage divider too.

This is for a bicycle lighting system? Needs the back light if it is LCD. I'd go with a color LED bar/dot display and just blink it twice a second. Turn the brightness up during daylight if it is needed, and way down at night.

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That's beginning to look like a good option. I really don't want to get into programming a pic chip. This is getting pretty complicated anyway. Maybe I'll just fix it at 13.2 volts and call it a day, and take along my mini RS multimeter.

There are some wonderful HID (metal halide) lights on the market but they cost big bucks.

For tail lighting I'm using a Cateye TL-LD1000 which is red LEDs and has its own AA batteries. This and an amber strobe (12 volts) from All Electronics, this will run off the battery pack (12 alkaline C-cells).

I'm using alkalines because I wouln't always have the ability to charge rechargeables, but you can always buy alkalines.

The headlights, at this time will probably be two 12 volt 10-watt MR16 bulbs (one flood, one spot). Though finding these bulbs is proving difficult.

If you're interested, here's some controllers:

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Reply to
Bruce W.1

You should look into a 3W Luxeon LED headlight.

I have a luxeon LED flashlight and it is much brigher than any other flashlight that I own.. It runs on 4 AA batteries for approx 4 hours.

- Mike

Reply to
Michael Kennedy

I second that idea. Though I'd probably go with a Cree LED if using more than one - they don't sell "bin numbers" their LEDs either meet specification or they don't sell them.

I put 56, 13,000 mcd, white LEDs in an auxiliary light on my motorcycle and it is very bright - easily enough for a bicycle under most conditions. In daylight it is more noticeable than the headlight low beam. Burns 3.4 watts and outshines the 50 watt low beam. Only cost $9 Beam angle on that is only +/- 10 degrees - so it won't replace the low beam at night

I have four Cree red LEDs in the tail lamp and it is way overkill . . I should have used just two. At $8 each Beam angle on those is 120 degrees

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