Project costs

A project log for Programmable Precision Resistor

A SCPI programmable precision resistor

sebastianSebastian 09/11/2023 at 15:270 Comments

I didn't really think about the BOM cost of my programmable decade resistor until I was asked. Then I also wanted to know. It is fairly difficult to put a number to what I paid, since I had a lot of components left from other projects that I could use. This includes not only cheap chip resistors and MLCCs, but also connectors, the microcontrollers etc.

Normally, I order my parts from mouser and digikey. For some of the industry-standard components, connectors etc. I also use local distributors (cheaper!). This is why I'll only give a very rough estimate for the per unit costs including taxes (and not including any shipping costs). For some of the parts like the PCBs there is a minimum order quantity that will increase the cost in most DIY scenarios.

Mechanical parts

#Description€ (est.)
1ELMA Stylebox 15 Standard (not new)50,00
2Front & Rear panels (Aluminum PCBs)5,00
3Rotary encoder knobs and key caps10,00
4IEC power connector + Fuse3,00
54mm banana sockets8,00
6Connectors, cables etc.2,00
7Mounting hardware2,00


#Description€ (est.)
1Mainboard PCB3,50
3EC2-12NU relays (or similar)73,50
4Precision resistors63,00
5Other components30,00

UI Board

#Description€ (est.)
1UI PCB2,50
3STP16CP05 constant current LED drivers10,00
4LED displays15,00
5Rotary encoder and switches37,00
6Other components12,00

Power supply board

#Description€ (est.)
1Power supply PCB1,00
1TRACO TMPW 10-11519,50
1NE-18 series power switch8,50
1Other components5,00


According to this calculation the total cost of the unit would be about 369 €. Quite a lot, actually. This doesn’t necessarily reflect what I paid for it though. One example: I bought 5 NE-18 type switches on ebay for about 2 € each. These are not necessarily the same as the ones provided by mouser, but both variants could be used.