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Good Digital Multimeter with frequency and capacitance measurements for $15

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  • May 31st, 2005 10:41 pm
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[OP]
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Oct 13, 2002
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synaptech wrote:Order samples from Maxim. You should be able to get all you need for this project for free if you use an analog switch to mux the inputs.
I already got two sample LTC1867s from Linear. It was the best I could find with 8 inputs, so that I would not have to use a separate switch. And only 16 pins, so it should not be too difficult to solder. The most I have done is 8 SMD pins. :lol:

I am interfacing them to a PIC18F2450 so that I can use it as a datalogger. :D

Now, where can I get free custom double-sided PCBs? :D I can't do toner transfer on the small SMD pads.

How did we get so off topic? :lol:
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Jan 23, 2002
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Hamilton
So you're not going to use a pre-amp or any filtering?

Back on topic: Do you have this multimeter?
[OP]
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synaptech wrote:So you're not going to use a pre-amp or any filtering?
Would a ferrite + decoupling capacitor be enough? I can survive with just 13-14 bits of resolution. I will have to see how much noise I get before stripping of the last bits. :D
synaptech wrote:Back on topic: Do you have this multimeter?
Yes I do. Feel free to ask questions about it. :)

No replies to this thread for a month, and after teddy boom bumped this, it is now all off topic. :lol:
Newbie
Jan 31, 2004
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keep in mind meters are not regulated by anyone so just because it says good to 700V it doesnt mean that it will work. Just in case someone has not heard, meters can explode in your face with higher voltages so for 15$... use it for electronics and dont test the 200+ voltages IMO.
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Jan 23, 2002
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Hamilton
mrken wrote:Would a ferrite + decoupling capacitor be enough? I can survive with just 13-14 bits of resolution. I will have to see how much noise I get before stripping of the last bits. :D
Depends on your expectations I guess. It's easier to test and/or replace an amp than your ADC. Also, you could also have your own scale instead of a 4.8V DAQ with a 60 Hz notch.

Have you tried the other functions - are they decent?
[OP]
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synaptech wrote:Depends on your expectations I guess. It's easier to test and/or replace an amp than your ADC. Also, you could also have your own scale instead of a 4.8V DAQ with a 60 Hz notch.
An ADC would add quite a bit of complexity... The entire board is under 1 X 3 inches with all of the connectors. Everything will be powered from a battery, so I don't think I will need any 50/60 Hz filtering. And I am sampling from a known source (8 AD8314s costing $14 each :D ) with an output from 0V to 2.25V. I guess I should design another board after this one with an ADC and adjustable gain. I am in a small rush to finish this, so I probably won't have time to make too many changes.
synaptech wrote:Have you tried the other functions - are they decent?
The capacitance actually seems quite accurate, at least agrees agreeably with the markings on the capacitors. :D Though it can only go up to 20 uF.

Everything else is just like the de facto Korean multimeters. Values differ from a LG multimeter by one digit for voltage and resistance measurements. Haven't had time to try the current tests. I've already blew enough fuses on my $10 DMM, and just replaced it with a screw. No problems so far. :D
Dazisgud wrote:keep in mind meters are not regulated by anyone so just because it says good to 700V it doesnt mean that it will work. Just in case someone has not heard, meters can explode in your face with higher voltages so for 15$... use it for electronics and dont test the 200+ voltages IMO.
I don't think I would want to measure 700V, nor would I find anything with such a high voltage easily. It works fine with 120V and 240V mains wiring though. Though I do use gloves and slippers/shoes whenever I do AC measurements. Got shocked once while inside a computer with my hand on the modem, during which the phone rang. :D
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Sep 12, 2004
245 posts
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Vancouver
Lee's is a great place. I've been going there for years. It truly is a "mom and pop" kind of store owned and run by Mr and Mrs Lee. I am pretty sure they don't ship, though.
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mrken wrote:I've already blew enough fuses on my $10 DMM, and just replaced it with a screw. No problems so far. :D
Until one day your meter melts! :razz:

mrken wrote: Though I do use gloves and slippers/shoes whenever I do AC measurements. Got shocked once while inside a computer with my hand on the modem, during which the phone rang. :D
Heh! Phone lines on-hook are -48VDC. Not a problem normally. When it rings, it jumps to 96VAC. I don't know what the current can jump to - I'd be guessing half an amp... maybe a little more. I certainly wouldn't want to lick that, but the odds of it killing you are pretty unlikely. Stings like a biatch though, doesn't it?!
[OP]
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seangoesbonk wrote:Lee's is a great place. I've been going there for years. It truly is a "mom and pop" kind of store owned and run by Mr and Mrs Lee. I am pretty sure they don't ship, though.
Run very professionally too. Has everything all categorised and uses a [rfdlink=autolink/redirectpage.php?linkid=167]Dell[/rfdlink] computer for their POS. :D
computer01 wrote:Until one day your meter melts! :razz:
It already has. :lol: There is soot all over the circuit board. I think that happened when I accidently touched 240V while in current mode. Heard a poof and before I knew it, the leads was already hot. But the other functions still worked! More than I expected from a $10 multimeter. Let see if this multimeter for $5 more holds up as well. :D
computer01 wrote:Heh! Phone lines on-hook are -48VDC. Not a problem normally. When it rings, it jumps to 96VAC. I don't know what the current can jump to - I'd be guessing half an amp... maybe a little more. I certainly wouldn't want to lick that, but the odds of it killing you are pretty unlikely. Stings like a biatch though, doesn't it?!
Wow! I never knew it was 96VAC. I had always thought it was just 48VAC. The stinging scared my pants off at first, but afterwards, it wasn't that bad. :D Just like licking a 9V battery for a first time. :lol:
DennyTang wrote:I thought these stuff were always usually around $15? Don't know what they are and what you would use them for, but infomicro.ca had a different looking one for $15 probably since last year.

http://infomicro.ca/Electronics/Electronics.htm
But the one here has more functions, like capacitance and frequency, although the one you linked to has a backlight. :D
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Sep 12, 2004
245 posts
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Vancouver
mrken wrote:Run very professionally too. Has everything all categorised and uses a [rfdlink=autolink/redirectpage.php?linkid=167]Dell[/rfdlink] computer for their POS. :D
Well, I've been going there for around 10 years now, and I remember when they were just using a printing calculator... :cheesygri

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