EEVblog #211 - IET Decade Resistance Substitution Box

What's inside a $500 commercial decade resistance substitution box from IET Labs? Dave's about to find out.

[douggale]

You must strike terror in the heart of manufacturers! You have no mercy when it comes to criticism of poor construction, however, your praise is high when deserved. Great reviews!

[GardeningZ]

I ordered an IET labs RCS-500, which is a resistor and capacitor combo box. It failed on the day it arrived. I just used it for about an hour. One of the "high quality custom made" switch was broken.

[dhpbear]

8:00 - Maybe that 10 MEGOHM range was calibrated using drips of flux :)

[NL]

There is a update in EEVblog #229 (from 17:28)
The 'hacked wire' is deliberately there.

[rogertopful]

For $500 bucks, I want perfect built not bodged.

[jan.tichavsky]

@neutron7 well for that price I would expect top class soldering, cleaned flux and no such solder joints, it seems they are cheap enough to not use new resistor there.

[danijel]

You do realise this is a bigger scam than those white van guys???

[OneBiOzZ]

its been 6 years, lets see if its still bang on!

[christopherperry]

DIY your own for 20 bucks with off the shelf eBay bits. Spend the other 480 bucks on booze and then solder together for Quality kit as good as the 500 bucks version.

[EEVblog]

Although you can get very expensive multi-turn pots with calibrated readout dials...

[penetrator]

You can get decimal pushwheel switches on eBay for around 5 bucks for a 10-pack. Add another 10 bucks for the resistors and the case and you saved yourself a ton of money.

[randacnam]

Mine has proper resistors in the tenths of an ohm resistance bank. Of course mine is also much older (the Unimax [not IET marked] switches have 1986 date codes and most of the resistors have printed text ratings instead of color bands).

[EEVblog]

@TheCrazyInventor I thought about trying that, but I have no doubt they'll be under the stated 25ppm

[EEVblog]

@mageepaddy Because the flux residue could potentially have a high leakage resistance (say 100Mohms). Put that in parallel with 1K and it makes no difference. Put it in parallel with 10M and it matters a lot.

[IndustrialGoblin]

@EEVblog Exactly! It will take massive amount of time to do that, especially if you need to set more than two values.

[MrJetra]

The code switches seem to equal APEM IR110ND (RS P/N:425-0805), though they are custom build. These swithes are extremely expensive just as standard parts (DKK 190 / $27 in todays RS price). That explains some of the high price.

[Tangobaldy]

If they stamped an apple logo on it then its worth $500. Looking inside its like a hobby kit made buy a noob. What a rip off.

[EEVblog]

@RSole52 The same way you can pay $50 for a quality connector...

[MostFolkCallMeOrangeJoe]

If they're creating switches with custom contact positions, Instead of using resistors of value (1, 2, 2, 2, 2), would it not be easier to use (1, 2, 4, 8), i.e. binary place values?

[EEVblog]

@JumperOneTV You'd have to disconnect from your circuit and measure it each time, kinda inconvenient!