Hi guys! Long time no smell.* I miss you guys, but I've been doing almost zero electronics. (I lurk every now and then) So my son wants a cheapish DMM for Xmas. What brand should I look at? Extech? Searching this Klein tool one looks nice. Klein Tools MM400 Multimeter, Digital Auto Ranging, AC/DC Voltage, Current, Capacitance, Frequency, Duty-Cycle, Diode, Continuity, Temp 600V ~$50 on amazon
George H.
*Did I recommend "Emperor of Scent" as a good read?
I had an Extech that I really liked because it was small, but very functional. However, they use these really cheesy banana jacks that solder surface mount, using a perpendicular point of contact, rather than bending the lead over and having a foot. So one broke off and I could never get it soldered back on. :(
I tried to order a new one, but these things have a half life like a laptop, some months, then they are discontinued and a new one takes it's place. Every unit I've bought since then used colors on some of the text that is virtually illegible against the chosen background color. When they change the background, some other text is now done with disappearing ink! So I gave up!
The frequency and capacitance are a bit limited typically, but if you have nothing else... The temperature uses a thermocouple, which needs a reference temperature. If you want to measure 600°, you should be fine. If you want to measure room temperature, it will always read the same thing unless they use some reference. I remember reading a temperature that was dropping when I expected it to rise. My furnace had kicked on and was blowing on the meter!
Actually, $50 sounds a bit pricey to me. You can find good meters for $25-$35. Eevblog has discussions with lots of meters mentioned. You might ask there. They also review a lot of them and promote some. I'm not sure if they actually worry about what they are promoting, so it may or may not be a recommendation. Or maybe your $50 meter has a good temperature reference, and is worth the money? It's really hard to tell with the Chinese brands.
Nice to hear from you again! My experience is that auto ranging can be painfully slow and does not make it to my list of desirable features. Neither is frequency nor duty cycle. Capacitance can be handy but DMMs tend to have rather limited ranges. Many low end units only have DC current but AC current (even if only LF) is a nice to have. Personally I like to have more than one DMM to hand, the second unit can be very low-end but seeing (for example) voltage and current simultaneously without swapping probes etc is great. A clamp meter with AC/DC hall effect current sensor is always in my toolbag, not much use at mA levels but very handy for general troubleshooting.
Yes. I do that too. Particularly useful for determining the temperature of cast iron skillets, especially with a puddle of oil in them. Also used to measure the air temperature inside the oven. Not useful for broilers.
What I have been using since 2007 is an Extech model 421501, which is a "Type K Thermometer". No problems so far. I bought it with a penetration probe, but it has standard thermocouple sockets, and so can be used with all manner of purchased or made probes. What I use for the skillets et al is a homemade Teflon-insulated type K wire probe about 2 meters long.
While one is supposed to weld the two wires together to take the TC, it also works to twist them tightly and soft-solder them together.
One can weld the wires together using a 100-watt incandescent lamp and a lump of carbon, drawing an arc between twisted wires (fluxed with borax) and the carbon lump. The 100-watt lamp will pass ten amps, and then drop to one amp.
Thanks, yeah totally getting the TC. Can you soft solder a type K TC? I use to use type T, easy to solder and not very magnetic. (Hmm maybe one for me and one for my son?) George H.
Thanks piglet, If there is a range button so you can turn off the autorange and just select one, then that works. I think mostly my son will want to check continuity/ resistance and low DC voltages and maybe currents. Nothing fancy just simple trouble shooting stuff. I trust you have plenty of haycorns packed away for the winter. :^) (2-3 feet of snow here and 5-6 just a few miles north of me. Lake effect in Buffalo, is fun and challenging.)
What I like about it is it's a rugged meter, I've been using one almost daily for about 15 years and still going strong. The buttons and rotary dial are solid and not made of that rubbery Chinesium crap that wears out fast with use like the Klein Tools meter maybe has..
I believe the 220 is discontinued but looks like an Amazon reseller still has some kicking around..
I'd bet that tinners flux (HCL plus Zn) would work. Failing that, stainless-steel (phosphoric acid) flux. Haven't needed to solder Chromel-Alumel so far, but have soldered lots of stainless steel hardware.
What also can help is to mechanically clean the surfaces under oil, to keep oxygen away from the freshly cleaned surface to be soldered. This also works on aluminum.
You're probably right that it can be done OK that way.
During the Battle of Britain, the RAF used to repair shot-up aircraft by attaching Al plates using plumbing solder under oil, so that one has a pretty good pedigree.
Plumbers' grease flux contains zinc chloride and ammonium chloride in petroleum grease, so it has more bite than radio solder.
I've found tinners flux good for soldering battery holder terminals to their riveted battery contacts. Apply with a wet toothpick. Rinse in hot water when done.
Yep, I very successfully welded TC junctions using a carbon rod (from a old dry cell) and capacitor discharge arc. Cannot recall details, but something like 200uF charged to 50V.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.