Triplett 4800 Review/teardown

[duskglow]

So as I mentioned in another post, I just acquired a Triplett 4800 on ebay for $25.  Upon receiving it, I noted that it had some bad contacts, and after covering them with aluminum tape, right as rain.  So here's a mini-review and a few pictures of its innards.  (two of those pictures were just for my reference so I could put it back together properly, but they give a good view of the input board and current shunt, so there we go.)

... and I know what "current shunt" is.  I'm getting somewhere!

Alright, so here's the skinny.  This is a pretty nice piece of kit.  The case itself is thick plastic, but it's not going to survive like aluminum would, the LCD display is not backlit and seems actually kind of cheap, the buttons are just contact buttons.  But it makes up for it with features.  This thing has:

Auto and manual ranging of volts, amps, and resistance
continuity testing
diode check

Basically, all of the common stuff.  But then you add on top of it:

Frequency counter
dbm meter
relative display
comparator
temperature
dual frequency meter
data and peak hold

A couple of those features deserve more exposure because I've never seen them anywhere else (though I'm not very experienced, so I might just be showing my ignorance).

The "relative display" lets you take a reading, then you hit that button (REL).  It zeroes out the display, and any reading you take past that is relative to the reading that's stored in memory.  So say you had a reference that was not the same as 0v...  you could take readings relative to that reference.

The "comparator" is a really interesting feature too.  You set a "hi" and "lo" setting for the comparator, and when it's enabled, it will alert if the reading is out of range (or is it in range, I haven't tried).  But not only that, there's a DIN plug on the back that lets you connect directly to the relay, so you can control other things based on the comparator output.  That actually has applications beyond just being a multimeter.  Speaking of that DIN plug, you also get an analog output showing the reading, so you can pipe that into something else.  I still haven't even figured out what I'd use that for, but a part of me thinks that setting that up with a raspberry pi could make for some interesting graphical abilities - such as a "poor man's scope" (though it would probably be kinda lame considering the counting speed of multimeters vs. scopes).

My impression?  This thing's kind of a workhorse.  And I haven't even gotten into the 1 nA resolution.  If you can pick one of these up on ebay, DO IT.  Even if the buttons don't work, just slap some home depot aluminum foil tape on it and you're good.  This is one of those deceptively old and cheap multimeters that are just packed with features.

Now to be fair, I haven't had a chance to test its accuracy or anything.  It's probably a bit out of calibration.  So this is just my initial impression, ymmv.  But it looks like when they get on ebay, they go for cheap, so it's worth picking one up anyway.

Oddly, when I opened it up, there was a wire anchored into the top that went nowhere.  This thing has no antenna that I know of, so I have no idea what it's for.  Ah well.

EDIT:  That first picture isn't so good.  I'll post a better one when I get a chance.  No one ever accused me of being a great photographer.

[duskglow]

I did check out the frequency on both the Triplett and Tenma today.  I used an iPad with a signal generator app and an "aux" cable.

The triplett was rock solid and VERY accurate (down to a fraction of a hertz).  The Tenma was all over the place, and for some reason, the count kept lowering.  So I'm not so sure I want to trust the Tenma as much after seeing that.  Id did smooth out a bit on a square wave, so I don't think it likes sines.