One of the things I like about dealing with Digi-key as a supplier for electronics parts is that they treat me like an important customer, even though I order only small numbers of parts. For example, they automatically send out notifications whenever a manufacturer informs them that a part is being discontinued—like the notice I got today:
Part Life Notification
Dear Valued Digi-Key Customer,
You have purchased the following part number from Digi-Key within the last two years. The manufacturer has announced an update to the part status.
Part Affected Manufacturer OSRAM OPTO SEMICONDUCTORS INC Description LED IR EMITTER 950NM Manufacturer Part Number SFH 4512 Digi-Key Part Number 475-2943-ND Customer Reference Number IR EMITTER Status End Of Life Last Time Buy Date 12/01/2014 Substitutes Please click here
It used to be that only big industrial customers got that sort of service—now even hobbyists, students, and professors can be kept informed about the parts they use. Digi-key doesn’t have to spend a lot to do individual notifications (it’s all automated), but it probably took them a fair amount of time to set up the system to do so, and this sort of attention to customer service is one of the things that has made me a loyal (though small) customer.
I’ll drop the IR emitter from next year’s class part list (we didn’t do much with it this year anyway).
I’ll also change the red LED from LED red diffuse 3mm 625nm WP710A10ID to WP3A8HD whose peak emission is at 700nm (where the molar extinction coefficient for oxyhemoglobin is only 290 cm-1/M, rather than ~683 cm-1/M for the 627nm peak of the WP710A10ID we used this year). Ideal would be a 686nm peak, where oxyhemoglobin is most transparent (272.8 cm-1/M), but there’s not much available between 700nm and 660nm (some more expensive ones at 697nm, which makes little difference from 700nm), and 700nm is better than 660nm.