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RES64 > RES15 (somewhat)

A project log for YGREC8

A byte-wide stripped-down version of the YGREC16 architecture

Yann Guidon / YGDESYann Guidon / YGDES 10/25/2019 at 03:022 Comments

I received 72× RES64A from Moldova and I'm pretty happy and lucky :-)

@Artem Kashkanov  praised the RES55 he uses : the lower current and the higher hysteresis compared to RES15 would be great and I was eager to test something.

The log 86. Sensing relays explored the question of the reed relays and found that even cheap 12V relays from China have desired features for certain circuits of the YGREC8 : mainly as sensors/amplifiers because they require much less current for activation.

I just measured a RES64A and the reference I received is pretty awesome !

The case is pretty bulky but this adds to the charm. With a suitable price, I'd get more of them and use the high hysteresis to build the register set as well.

Even at 2.5mA (worst case), the gain is really significant ! It is less than 1/10  the current required by the RES15 and the hysteresis is somewhat higher, which means : much more stability ! And no need to bin the parts !

Total current : 2.5 × 8 × 8 = 160mA max !

This considerably relaxes the constraints on the power supply, the ripple (and filtering capacitance) is much less and the whole is less sensitive to interferences...

However the supply voltage would be 4.3 + 1.7V = 6V and I'll have to find/design the proper power supply and transformer... But 6 × 0.16 = 1W max !

Now I have to find enough vintage Russian 2K resistors...

There is another change : the RES64 is SPST so it's only on or off... the RES15 is SPDT and can switch the output from +Vcc to -Vcc so it's pretty convenient for the output levels. A register set made of RES64 will require some sort of buffer (maybe another RES64 per bit, so I'll need 72 of them)

Discussions

Artem Kashkanov wrote 10/25/2019 at 06:06 point

You got relays and put no photos?? Huh!

I praised not only RES55 - RES64 are also good enough  - but you should notice that load current for this types of reed relays shouldn't be greater than 100mA.

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Yann Guidon / YGDES wrote 10/25/2019 at 11:38 point

"no photo" => I already made 2 videos today (on another part of the project), just be patient ;-)

Load current : yes it's a known weakness so the only thing one RES55 can do is drive one coil of RES15. That's why they are good as buffers or latches, not computation. The RES60 is more adapted for this :-)

Anyway : the less current is switched, the better, for all sorts of relays. The contacts suffer mechanically and it's worsened by the inductive loads, so I also do my best to reduce the pulse current (with the help of capacitors for example)

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