Hello
Solid state relay is not working as I expected, could someone explain please.
SSR's come normally 'high' or 'low' – passing current or not. I've used normally 'high' and that worked as expected - it had to be trigged to pass a current.
I expected the normally 'low' to just pass a current without any triggering or powering to be necessary, it doesn’t.
After a bit of research I found an answer that seemed to say a load (on the switched side) had to be on the SSD for it to work – something to do with tri(something). As I want to switch 6v I put a 6v load on and 'it didn’t work'.
could the SSD be faulty or am I doing something wrong.
SSR's come normally 'high' or 'low' - passing current or not. I've used normally 'high' and that worked as expected - it had to be trigged to pass a current.
A relay is a switch.... It's either open or closed, not high or low... High or low depends on how it's wired.
Mechanical relays are often double-throw, which means they have both normally-open and normally-closed connections. SSRs are almost always normally-open. (I've never seen a normally-closed SSR.)
"Normally", relates to the non-powered or resting state. i.e. A normally-closed mechanical relay makes a connection and allows current to flow through the contacts when no power is applied to the coil.
SSRs are designed to switch either AC or DC and you must use the appropriate type.
It's common for SSRs to have a minimum voltage, so an SSR designed to switch 120/240 VAC may not work correctly with 12 VAC.
... and then there's the opto-mosfet type SSRs that can switch low level signals and handle reasonably high voltages like this one. This type of SSR is available in Form A, B, AB, C and multi-pole.
Regarding the cheap SSRs found on eBay and such, some are clones with limited performance. A few of those advertised with 3-32VDC control actually need 12-32VDC to switch properly.
SSRs are almost always normally-open. (I've never seen a normally-closed SSR.)
think that explains why the thing is not doing what I wanted, that + my misunderstanding of high & low, I had thought it related to setting the thing to high or low in the arduino code
I've had/have trouble with mechanical relays and magnetic field interference with the rest of my circuit (two different projects) i'll have to have a think about how to work around this
should be able to do something using diodes
You were talking up switching "6V" in your original post.
You likely have an SSR for switching AC voltage.
Can't you take a picture of that it and post it?
Sorry if it agitates you or anyone else, but I think that you ask many questions and answer very few, and you should be more forthcoming in providing details.
You can do whatever you want, but this thrashing about and implementing indiscriminate "solutions" stuff will get you nowhere.
The interference problem discussed in the link provided by Runaway Pancake would be relatively simple to resolve because you've provided:
● Part number (2 Relay Module)
● Image of connected devices
● Description of load 240v 35W Reptile Heating Pet to be replaced with 75W
● Description of problem "but as I said it is working when no load is applied."
The description of problem points to an easy, low-cost solution.
Here, we still need a part# and image of setup or circuit diagram. Otherwise, its just guessing.
Thanks in advance.
Its not that it agitates me so much as a good percentage of the answers go beyond my understanding and me asking 'what do you mean' will not directly sort the problem but will bog me down in a steep learning curve, long term good, short term a distraction.
The thing from last month (which i tried different solutions to) was a different project, changing from a mechanical relay to a SSR and moving the high voltage away from the rest of the components did work. Was an aggravation but i did learn a few things.
I'm now revisiting an old project (solar powered pond pump) that i never managed to get to work properly, I think the problem is again the mechanical relay magnetic field.
I'll write out a fuller description tomorrow - if you dont mind drip feeding me explanations
dlloyd
you posted just before me, but as you'll see that project now works and i'm trying to sort a old project, i'll post tomorrow with more info
but thanks for tacking notice
As your no doubt gathered by now electronics is not my field, the Arduino and components allow people like me to make things that once wasn’t possible – lack of basic electronics knowledge can be a wee bit of a problem though
I'm attaching three images, a photo of my project, a circuit diagram, a possible solution
the project is to run a 6v pond pump from a 6v solar panel when the suns shining or switch to a buck step down power supply when the sun is not shining. The step down takes its power source from the Arduino 9v and steps down to 6v
The relay – which is I think giving problem
Unfortunately its necessary that the relay is normally closed - even if project is switched off the 6v from the solar panel will power the pump. And apparently a SSR will not do this and a mechanical relay which will do this is giving problem.
So I’m probably going to suggest something thats impractical, will the attached rough drawing work or is their a better way – probably is
It has a number of errors which need addressing. Like SSR stepdown wiring + and - connected with diodes.. which would not allow it to be energized if wired that way... under any conditions.
Well i did say the sketch was rough, though i didn't mean it to be that rough, diodes the wrong way round and the solar input should be '-' on the right hand side
really must look twice before posting
but other than my carelessness would it work ?
The capacitor, means a trip over to maplins to get on but worth a try
Unfortunately, this module does not offer opto-isolation ... but I wouldn't give up yet. When both relays are turned on, what is the voltage from VCC to GND at the relay module?
Please try this: At the relay pins, take the grey (GND) wire and red (VCC) wire and wrap them through the hole of a ferrite core as many turns as possible (hopefully 5-10 turns each) They can share the same core.
