Voltlog #183 – Building A Resistance Standard With Vishay VHP100 Resistors

Welcome to a new Voltlog, today I’m going to be building a precision reference box, using these precision Vishay resistors, they were sent to me for free by Vishay, these are from the VHP100 series and they are the ducks guts when it comes to resistors. They have incredible stability, across the entire range of -55 up to +125 degrees Celsius they will vary less than 60ppm. So as you can see they had to define the number over the entire temperature range because if they would have done it traditionally per degree C the number would have been essentially 0.

These are built using a special technology called bulk metal foil, wrapped on a ceramic substrate. Then the assembly is suspended in oil and hermetically sealed in this metal can, thus it’s immune to humidity changes. Every one of these resistors is basically custom made so you can order them in any value, but as expected they don’t come cheap. Purchasing these in some standard values carried at the big distributor will cost you around $70 a piece.

Voltlog #180 – Vishay VHP100 Foil Resistors With Zero TCR

If I get this built correctly, with the performance of these resistors, once the box is finished and calibrated it should be good for life. Because I would only be using it in the lab which regarding the temperature varies from 20 to 30 degrees C maximum.

The construction video will follow soon after I receive the aluminium enclosure, until then thank you for watching this and don’t forget to subscribe and hit the small bell icon to be notified of new uploads.


Voltlog #173 – µAmp Current Source

Welcome to a new voltlog, today we are taking a look at a very interesting item that was sent in by a viewer of the channel. Fabian who is from Romania sent me this microAmp current source that he designed and built himself. Even though he built only a few units by hand it looks professional and you must have noticed the resemblance with the uCurrent built by Dave from eevblog, but that gadget is used to measure small currents while this one is used to generate small currents.

Link to the uAmp Current Source on Tindie


Voltlog #166 – LRC Reference Box (Hao QI Xin)

In this video we are taking a closer look at the Hao QI Xin LRC Reference Box which contains a couple of polystyrene capacitors, a vishay precision resistor and an un-marked inductor. I also talk about getting the AD584 voltage reference box, however it is hard to find the LH version as most seller will be sending you the KH version which is a lower grade of stability.

Here are some links mentioned in the video: