• Testing three different relays

    matseng11/04/2016 at 15:59 5 comments

    [ A severe brainfart made me type us instead of ms in this post. It's now corrected. Thanks @Yann ]

    I bought three different cheap & small 12 volt relays and tested them at 12.0 volts.

    The blue is a SONGLE model SRD-12VDC-SL-C
    The black is a SONGLE model SRC-12VDC-SH
    The yellow is a HUI KE model HK19F-DC 12V-SHG

    The blue is much more noisy than the two others, probably because it's a bit more heavy-duty supporting up 10 Amps at both 250 Volt AC as well as 30 Volt DC. It takes 2.5ms to start moving the reed after power is applied and then some fast bounces and is stable after 4.6ms. This is about the same as the other two relays. But the de-energizing is clearly different - almost double the time compared to the others to start dropping the reed, and then spending a long time with really slow bounces clocking at at 7.1ms. The spring pulling back the reed in this relay might be very loose to get this bounciness.

    Blue Songle SRD-12VDC-SL-C

    Looking at the other Songle relay, the black one we can see that it takes quite a while to start moving after energizing, but spends less time between the poles and finished up in about the same time as its bigger brother. The de-energizing is just 0.5ms to start moving followed by a short burst of bounces and stabilizes in a nice and fast 2.2ms. So the total time is 7.1ms meaning that we in theory could fully switch this relay on and off at rate of 140Hz

    SONGLE model SRC-12VDC-SH

    The final yellow HUI KE relay with the same form factor as the black Songle is rather similar in the electrical characteristics as well. It bounces a bit more at energizing and is a tad slower at de-energizing.

    HUI KE model HK19F-DC 12V-SHG

    These differences on the black Songle and yellow Hui Ke might just be coincidental and might also show up on different specimens of the same model. I need to get a few of each and see if there are any major variations within the same type....

    But first I'll run some tests and see if the 5, 12 and 24 volt models of the relays have any noticeable differences in speed and bounces. And also make some graphs in Excel of the energizing times when the voltage is varied +/-50% of the nominal coil voltage.

  • Mounted on acrylics

    matseng10/26/2016 at 06:15 0 comments

    To get it all a bit more stable and prettier I soldered 1mm copper wires from most of the mounting holes in the modules and stuck them into a piece of acrylic and just bent the wires over at the bottom. It turned out not too bad in the end... ^_^

    I also added the missing boost smps and a dismantled ftdi module (the red at the top left corder) and glued it down onto the acrylic securely so I can use that USB connector as the main supply input. Then I don't risk working any of the connections on the Nano loose by plugging/unplugging the USB connector on it all the time.

  • Block diagram

    matseng10/25/2016 at 07:08 0 comments

  • Patching modules together

    matseng10/24/2016 at 02:27 0 comments

    Not having access to my own lab while travelling I used the very nice Makerspace in Penang, Malaysia to just hook up some modules I got by mail order to some parts I got from the shelves of the space to cobble up an ugly contraption worthy of being called a hack. ^__^

    I got an Arduino Nano (not used as an Arduino, just for the '328 on a PCB with USB), a SD-card reader module, a Nokia LCD module, a LED voltage meter module, a boost SMPS module (which I promptly lost, therefore not visible yet on the pictures, a replacement is on order) and a handful of miscellaneous parts like a LM317 variable vreg with a potentiometer, a LM7812, a IRF640 MOSFET, buttons and a Rotary Quadrature Encoder on a small donut board.

    Patched together with single core hookup wires it looks like a total mess from the bottom - the top looks a bit better though. :-)