And here is the second part of the $1 multimeter deal from the last Hamfest. Together with Micronta 22-201U analog meter reviewed here I picked up this 3.5 digit digital one of a similar age. The poor thing looks like it had a rather difficult life!
I’ve been lucky enough recently to score a Keithley 2304 power supply off ebay for a measly $75. For those unfamiliar, these are high speed battery simulator units capable of measuring very low currents and also behaving like a battery and sinking current.
Original ebay picture
Today we have two tiny multimeters to take apart and see what we can learn from how their designs progressed:
On the left is Hioki 3217 and on the right – Beckman DM78
The latest addition to our vintage collection is a Keithley 130A handheld DMM from the mid-eighties.Keithley is not well known for its handheld DMMs, or at least I’ve never heard of them. It’s a 3.5 digit 0.25% instrument made in mid 1980s
The thing is tiny! Shown next to the EEVblog uRuler
I’ve been looking for a good clamp meter for a while now. While there is plenty of no-name cheap meters on Ebay, I figured I’d wait till something better “washes ashore”. So when a Yokogawa meter got caught in my ebay filters one day, I grabbed it. Yokogawa is a Japanese company, well known for their power measurement equipment. This meter has a nice mix of AC and DC current ranges fitting my low to medium current measurements needs. It is also a recent model, still being made and supported- a rarity in my lab setup of 20+ year old equipment Continue reading
Another ebay find- a vintage Keithley 172 multimeter. The datecodes on the parts range from 1978 to 1984, placing the final assembly somewhere in mid-1980s. It seems fully functional, but could use a bit of a calibration to regain its past precision.
An ebay find made its way into the lab- an industrial quality DMM from Hioki, made in 1984! The meter has some pretty good specs as shown in this datasheet:
- 3.5 digit (1999 count), 0.5% on DC voltage
- 20uA DC current range with 10nA resolution
- 1G input resistance on 200mV range
- Drop proof to 1 meter
- Dust sealed.
- 500 hours battery life using 2 AA
- Neon indicator of overvoltage Continue reading
Today we are unpacking a brand new LCR meter from a company called Tonghui in China. It was purchased on ebay and took less than a week to arrive.
Chinese market packaging
Today’s quick teardown target is a 1985 vintage electronic load made by Kikusui of Japan. It came from eBay with a noisy fan, but was otherwise fairly functional despite the considerable age.
Only 2 inches wide