so i have shared the it’s schematic and board design with the eevblog.com community and they said “that this module will not work and the relay contacts and board tracks can’t handle high current” I improved and made the board anyway and tested it with inductive and resistive loads and it works without a problem huh
(squints)
Looks fine up to about 6 amps I reckon, judging from the size of that relay. Not a huge high power coil on that so a simple npn transistor switching the coil to ground would be fine. Got a diode across the coil to catch the back-EMF, looks like all the basics are covered .Would only bother adding extra solder to the tracks for the relay contacts if I was doing it but that’s neither here nor there.
Dunno what those eevblog folks are on about 🤷
forgot to include this
I already added solder to the relay contact tracks to increase it’s thickness
Looks fine. Mayyyyyyybe the 1k resistor is a little high, depends on the gain of the transistor. 5 volts would feed it with 5mA on its base, which might not be enough to fully switch it on. However, as it’s only driving the relatively high resistance coil in the relay it’s nothing to worry about if it works.
If you were driving it with 3.3V, I’d probably swap that transistor out for a Darlington pair to make sure the gain is high enough to fully switch on at that kind of drive voltage. You can get Darlington pairs in the same pinout as normal transistors so it would be a straight swap on the board.
Having said all that, if it’s working in your application, leave it. 🤷
yup that’s true, i usually do my work with 5VDC , but i will switch to a Darlington transistor if i need to work with 3.3VDC in the future, thank you for the advise. 👍
I think the connected wires would vaporise before those tracks …
those are for the low voltage control pins for a gpio (to control the transistor and the supply +5v and GND)
I think it would help us if you included the part designators for components on the board, and then what your design criteria was. After all, this might be fine for 1A at 5vdc but fall apart for 10A at 67vac.
yeah sure
The manufacturer has rated this relay for nominal motor (ie inductive) loads of 0.5 A, with peak surge of 2.5 A, at 120 VAC. The flyback diode should be sufficient, since the switching rate would not be very high to control a relay. The terminal block supports a max wire diameter of 1.5mm2 (~16 AWG) which would be more than plenty for a 0.5 A load.
If you’re actually running >60 VAC through the relay, then it’s good practice to add a slot that prevents creepage currents between the low-voltage DC section and the higher-voltage power section.
For smaller applications, this seems reasonable enough, at least to me.
for 240V AC this relay can handle 5 Amps
