At the start of 2019, I found a very interesting item on @qro_team 's eBay store : a single box of 40 low-voltage РЭС60 relays. I wish there were more !
It's the real deal : it's DPDT (unlike the РЭС15 which is only SPDT), it's very small (great for density) and the version I have can turn on at around 2.5V at half the current of the РЭС15.
The DPDT part is very important for several circuits, for example the incrementer for PC and the ALU. But today I focus on other less visible parts : the bit sense circuits for the memory arrays. The DRAM uses capacitors that will discharge in the coil and the lower current increases the reliability of the whole system (less sensitive to current leaks in the capacitors). The instruction PROM (on which I work at the moment) also benefits from a lower current because each line drives 16 bits and the aggregate current is then handled by a single relay... So if a current of 10mA is enough to trip one line sensor, the worst case scenario for the main driver is 160mA, which is within the tolerance of the РЭС15. It remains to be seen how long it remains reliable but this is another debate. I could make the "single point of failure" easy to replace.
The РЭС60 I have are sold as "6 to 8V" with a coil that measures about 66 ohms. It's a -02 type (?) and all the others I find on eBay have a much higher voltage : 18V, 23V, 27V, 34V... They would certainly have a lower driving current but the voltage swing is not practical. I could try my luck if there are "12V" versions but I need another box because the 40 pieces I have at the moment is barely enough for the various circuits that require it... Who could help me ? @Artem Kashkanov ? @[skaarj] ? ...
According to this datasheet (and many others found online),
there must be a marking error on my box because the -02 is rated at 270 ohms and I measured coils in the 65 ohms range... but apparently I need a 12V version, with -02 or -08 type (I still can't get the difference).
I might have found -04 (lower voltage) that would be useful in the ALU so my -03 would be used as sensors, probably using pre-biasing, unless there is some magic reed relay that could save the circuit ? (Artem ? ;-) )
Correction : the box is marked "00.02" so according to the references I have found, it should be a 23-34V version. Measurements disagree... I don't know what happened or if the parts were repackaged but anyway, I have them :-D