What is the smallest voltmeter?
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From: Bob Masta on 1 Feb 2007 08:02 On Wed, 31 Jan 2007 18:45:07 GMT, "Bruce W.1" <sorry(a)noDirectEmail.com> wrote: >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. 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 www.daqarta.com Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!
From: default on 1 Feb 2007 12:26 On Thu, 01 Feb 2007 13:02:01 GMT, NoSpam(a)daqarta.com (Bob Masta) wrote: >On Wed, 31 Jan 2007 18:45:07 GMT, "Bruce W.1" ><sorry(a)noDirectEmail.com> wrote: > >>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. > >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 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. -- ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =----
From: Martin on 1 Feb 2007 12:49 On Jan 31, 9:04 pm, e...(a)FreeNet.Carleton.CA (Michael Black) wrote: > "David L. Jones" (altz...(a)gmail.com) writes: > > > > > On Feb 1, 7:03 am, "Bruce W.1" <s...(a)noDirectEmail.com> wrote: > >> David L. Jones wrote: > > >> > Less than 1" wide: > >> >http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=9932909 > >> > Standard 200mV FSD, just make your own input scaler. > > >> > Dave :) > > >> ================================================= > > >> Expensive little guy isn't it? > > > What's your time worth? > > If it's worth nothing to you then yes, it's expensive, otherwise it's > > not so expensive. > > You might be able to get it cheaper elsewhere. > > Of course, one can make a tradeoff. Go bigger, and the selection goes > up and the prices drop. Low end DMMs have become so cheap that using > one as a dedicated meter is not outrageous. But then, the original > poster wants small. > > Or get a cheap analog panel meter, even one of those surplus "tuning > meters" that have a calibration that doesn't mean a thing. Make > the scale. Put a zener diode in series to get expanded scale, so it > reads the range you want. > > The poster can figure out what they really need the meter for, and > then come up with some scheme that does the job without overkill. Some > LEDs and comparators, or one of those voltage level ICs (their proper > name escapes me at the moment), so they get discrete steps. Do you mean LM3914 http://www.jameco.com/Jameco/Products/ProdDS/24230.pdf I used 2 of those and a pair of 10 LED bargraphs to make a very nice 20 LED analog voltmeter for my motorcycle, which has charging problems The LM 3914 can be used anywhere from 3 to 18 volts or so with Very minimal support circuitry. Offhand, I believe the OP could make a 10 segment meter with: an LM3914, the LED bargraph and 2 or 3 resistors. If he needs to calibrate the upper and lower thresholds more precisely, he would need to add two pots to that. > Maybe > making sure the voltage is merely "good" and "too low" is sufficient, > so two comparators driving two LEDs is sufficient, or there are neater > schemes to have LEDs turn on at a given voltage. >
From: Bruce W.1 on 1 Feb 2007 19:57 Bob Masta wrote: > > > 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 > www.daqarta.com > Scope, Spectrum, Spectrogram, Signal Generator > Science with your sound card! =============================================== 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: http://www.cs.indiana.edu/~willie/lvr.html http://www.lasertagparts.com/lightbrain/index.htm http://www.quickar.com/tkit.php?session=Rb0v0Fx5 http://www.trailheadlights.com/
From: Michael Kennedy on 3 Feb 2007 17:36
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 "Bruce W.1" <sorry(a)noDirectEmail.com> wrote in message news:X%vwh.5314$zH1.3172(a)newssvr29.news.prodigy.net... > Bob Masta wrote: >> >> >> 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 >> www.daqarta.com >> Scope, Spectrum, Spectrogram, Signal Generator >> Science with your sound card! > =============================================== > > 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: > http://www.cs.indiana.edu/~willie/lvr.html > http://www.lasertagparts.com/lightbrain/index.htm > http://www.quickar.com/tkit.php?session=Rb0v0Fx5 > http://www.trailheadlights.com/ > |