I love these hacks! I question the logic to hack the cheap gear but this is more about artistry and 'climbing the mountain because it's there' rather than reason (or functionality). I mean, if you are trying to prove a point, then the cheaper the gear the more interesting the hack.
Hi Caleb, thanks, nice collection, there are some smart guys out there.
I have a Fluke 8050 (page 4) - although about 40 years old now, they are a great bench meter but the displays go black after some years - maybe that's why the guy did the mod?. I was lucky enough to find a replacement one for mine about 20 years ago and since then it has been good, but I'd look at doing something like this if it went wrong again. I've also seen a mod that replaced the LCD with 7-segment LED displays (and it is referred to in the article you link to) - I downloaded that as insurance, as I will this one! I also have a Fluke 8020A - 3-1/2 digit little brother of the 4-1/2 digit 8050A - and had the same problem with the LCD and was also lucky enough to find a replacement. But you could do a similar mod there.
Incidentally, you refer on page 4 to a "Fluke 8050A Scope" - I think you meant DMM?
Page 3 shows how to make a temperature meter with a cheap DMM. However it only works from +10 to +125 Degrees C. Not much good in Canadian winters...
The datasheet for the ICL7106 (which is almost universally used in these meters, along with its lower power sister the ICL7136, shows how to make a temperature meter using an NPN transistor and 3 resistors, a cap and 2 presets. I've never done this but I know someone who did, I think it will do negative temps as well.
The LM/TMP35 used above gives an output voltage proportional to degrees C, but the LM335 gives an output proportional to degrees K. Although this is more difficult to work with, it should be possible to use that and make a degrees C (or F) reading thermometer which does negative temperatures. You can use the ref pins on the ICL71x6 to provide a stable offset to give a zero reading - as in the ICL7106 datasheet app.
Very informative article. I really liked the idea of converting digital DMM into temperature measuring device. Best part about all these ideas is that they can be easily realised with little investment. Looking forward to more such ideas.
I've seen many ways to measure temperature with a DMM. One uses a bipolat transistor relying on the PN junction. Voltage changes with temperature. You do have to linearize in software. You can do the same with a thermistor. I used to have some code that worked with a 34401A to convert resistance to temperature in a PC.
If you ask around on the LabVIEW or VEE e-mail groups, you can probably get someone to send you their code.
I created a small interface board for my Mitutoyo Caliper (with electronic interface) to convert the signal to connect with a parallel port (LPT) on a PC. I then read the data directly into Excel. It was documented in my book "Excel by Example" Only availabale on Kindle now. I would be more practical to convert it to serial nowadays (I wanted to show how to connect to the parallel port back then).