Solid State Relay opearation with Atmega16

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Hi to everybody!
Have anyone tried to operate SSR (of rating 230V AC load, 4-32 V DC control)?
I have done that but not succeded !
Right now control signal of the SSR is directly fed by microcontroller pin.
Pls let me have some guidance on it
Thanks in advance!

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Thanks for the loads of information.

I think it´s the green wire with the bad solder joint ;-)

Please tell us:
* the type of SSR.
* your operating voltage of the AVR, maybe also speed and compiler type.
* your code
* an error description. (what do you expect, and what is not working as you expect)

Also if by hand:
* the schematic

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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Ok let me describe it properly!
The SSR is connected to the OCR1A pin of the controller.
OCR1A pin sources the SSR.
Operating voltage is +5v.
And the SSR requires 6.5mA of current to get fully driven wich should be directly operated by Atmega16 pins as its maximum current capacity is about 200mA.
But Atmega16 can not drive it when OCR1A pin is high.
What would be the cause?
The SSR used have optoisolator on control side to drive the MOSFET on load side.

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Also let me know can SSR be switched ON without conneting any load at its o/p terminal?

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Spec sheet or part number on the SSR?

You should be able to switch an SSR on without a load. Also, you probably have at least 4 pins to connect on the SSR: +5V, Ground, and the two switch contacts. Make sure you have at least these.

You need a digital multimeter to check it out fully:

1. Make sure your pin is actually going to 5V.
2. Check the switch on the SSR to see if it is closing using the DMM.

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Quote:

You should be able to switch an SSR on without a load.

Not always. It may only be a few mA but some need a bit of a load.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Quote:
Not always. It may only be a few mA but some need a bit of a load.

Yes: The datasheet wil tell you:
There you can see something like: "min. current to keep switched on"
Also you need a min. voltage at the output side.
Also you need a min. voltage on the input side.

Quote:
Atmega16 pins as its maximum current capacity is about 200mA.

Where do you know this from?.
This is definitely NOT the recommended operating area written in the datasheet.

Please read datasheets of the devices you want to use.
There you can read if your circuit will work or not.

Quote:
SSR requires 6.5mA of current

So it´s on you to calculate a current limiting resistor.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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- terminal of SSR is connected to GND of the system.
+ terminal connected to OC1A pin.
Load terminals are fed to the AC load(fan).

Quote:
Atmega16 pins as its maximum current capacity is about 200mA

Yes, I knew it is maximum limit of the controller but not recommeded.
But if SSR requires 6.3mA current to be driven fully then why it can not be ON when the OC1A pin is 1(high) even SSR pin is directly connected to OC1A (without current limit resistor)?

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Quote:
- terminal of SSR is connected to GND of the system.
+ terminal connected to OC1A pin.
Load terminals are fed to the AC load(fan).

It really depends on your SSR type. We can´t help you if you don´t tell us.

Quote:
Yes, I knew it is maximum limit of the controller but not recommeded.

NO. Read datasheet!.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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SSR type???
On its nameplate following is written:
"TYPE VE 4825
INPUT 4-32V DC"

If u want a look then go to hte link


My SSR is of different mfg. but the same rating and appearance as in the above link.

Ok you are right about the current capacity of I/O pins. Thanks for guide me.

Quote:
DC Current per I/O Pin ............................................... 40.0 mA

But still it is much less than 6.3 mA.
For 200mA ,I might understand Vcc and GND pin capacity.
Now any clue for me?

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Finally you sennt us the type of the SSR.
..And a picture of an SSR. Is this exactely YOUR SSR?

But a type and a picture is no datasheet.

Maybe one of the readers have been working with exactely your SSR type. Maybe he can help you then.

But for all others - including me:
Do you want us to do the internet search for you? I think it´s on you to supply us with the necessary informations.

If you don´t have a datasheet of your type of SSR then the only thing you can do is: try.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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What is the Mfg name on the SSR you have?

This will be needed in hopes of finding the correct data sheet.

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All SSRs are not the same! So for us to guide you without knowing exactly what one you're using and have access to the data, we're just guessing.

Try a simple test - use a 9V battery on the input to the SSR and connect up a light bulb with some power on the output. This will test if the SSR is basically operating. Then you can try connecting it to the AVR. At the moment, you problem could be anywhere from the code in the AVR, to the way you've connected it to the SSR being faulty etc etc.

Most SSRs are triac based for switching AC loads - but you mention MOSFET - what gives you this impression? You SSR might not lick being fed pulses from the OCR1A output - write code to turn it on or off - not pulse.

I tried Googling for the number you provided - no luck. If you don't have data on the SSR, then you don't know what it is - either find one with data or persist in guessing and fiddling.

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Hi

Geez, trying to get blood out of a stone.
Did look at the picture you referred to & it means nothing to go on.

Can you upload a picture of your actual SSR here.
Or give us all the details what is written on the label of the SSR, lines by lines.
Then we can take it from here, otherwise we are shooting in the dark.

Kartman's testing is right in testing the SSR.
SSR do require a minimum load on the AC side to operate correctly.
Another idea is to put in parallel a LED & resistor across the 4-32V terminal.
Here you can see what is going on with your software control.

Maybe stupid question.
Do you have the power from the wall socket turn on ?

Ken

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Me again.

Where do you know about 6.3mA?

Quote:
and connect up a light bulb with some power on the output

I´ve seen SSRs that need 500mA min. load current to work properly.
Maybe your SSR is overloaded with 500mA.
- Noone knows what load to use...

Mind: usual light bulbs have a low resistance when cold. This means much switch on current.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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I've never had any problem when driving an SSR. That is, I've always been able to properly & reliably drive the 3-35VDC input of the SSR.

However...

If using the SSR output to drive an input or a device (such as a PLC input) that exhibits a high input impedance, there may not be enough current low to allow the output device within the SSR to operate. In this case, an artificial load must be used to provide enough load current to let the internal components of the SSR to operate properly. This wastes power as, a resistor is usually used and, there are always the I^R losses associated with resistive loads.

If the above is the case, it is my contention that the SSR is not the most appropriate choice to use for the power control mechanism. In this case, I would simply use a standard physical relay that meets the appropriate electrical and mechanical specifications.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Quote:
Where do you know about 6.3mA?

I had measure by DMM with +5(from SMPS) given to + terminal of SSR.
The mfg. name is semron but i don't think u get it anywhere on net.
Anyway, Thanks a lot all of you for such a kind and informative reponse.
keep in touch ,
Thanks once again!

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I'm intrigued by this thread - how on earth is it possible to reliably write software for a device for which one does not have a datasheet? If it's just a hobby project I guess it doesn't matter, if it's something professional it seems like madness to me. (doubly so when mains voltages are involved)

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WrightFlyer wrote:
I'm intrigued by this thread - how on earth is it possible to reliably write software for a device for which one does not have a datasheet? If it's just a hobby project I guess it doesn't matter, if it's something professional it seems like madness to me. (doubly so when mains voltages are involved)

Well, for the typical SSR, the specifications between the typical manufacturers are close to the same, else they can't compete within the SSR market place.

krunal_299 wrote:
...operate SSR (of rating 230V AC load, 4-32 V DC control)?

The OP has the basic specifications to successfully use this SSR. What he lacks is probably some detailed understanding of the relationship between the output of the SSR and the load which he is attempting to control. As long as hedoesn't violate the maximum current, voltage and power rating of the devices output section, he has what he needs to safely us this SSR.

The important parameters are:
1. Input voltage range.
2. Input current to turn on the internal Optocoupler
3. Maximum output voltage.
4. Maximum output current.
5. Total device power dissipation.

All SSR manufacturers make huge attempts to meet specific specification.

The exceptions would be specialty devices where, the input voltage would be specifically stated and unique, differences in "Zero Crossing", speciality output voltages and, proportional analog input control.

If the OP goes to say, Digi-Key, Mouser, Newark, Carlton-Bates, etc..., he would see that the specification for SSR devices are typically very well defined and, with few exception, the data-sheet for one SSR device will generally be applicable for pretty much every other SSR manufacturer offering that SSR class device.

In the final analysis, the important operating specifications are printed on the device legend label in every SSR that I have used.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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OK guys!
I have put transistor driver to drive the SSR control pin. CKT is : base is connected to OC1A through 1K,Collector is to +12 with pullup of 1K, Emitter is to GND.

It works good.
I have measure current drawn by SSR control i/p with DMM again wich is of same value 6.3mA.
My surprise is mainly to know why controller can't drive the SSR directly though it requires 6.3mA current whereas Atmega's I/O capacity is around 40mA.

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Quote:
I have put transistor driver to drive the SSR control pin. CKT is : base is connected to OC1A through 1K,Collector is to +12 with pullup of 1K, Emitter is to GND.

It seems you like to put riddles in the forum: At least I can not find any information on how you cennected the SSR.

Also You never answered wher you have the 6.3mA from.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

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Hi

Good to hear you got it working.
Looking at the M16 datasheet the voltage when High is 4.2V & Low is 0.7V at 5V.
You measure the pin voltage in both state to see what does it read on the DVM.

As explain above
- terminal of SSR is connected to GND of the system.
+ terminal connected to OC1A pin.

Could have done the opposite
+ terminal of SSR is connected to +5V of the system.
- terminal connected to OC1A pin.
Need to invert OC1A signal in your code.

Ken

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krunal_299 wrote:
OK guys!
I have put transistor driver to drive the SSR control pin. CKT is : base is connected to OC1A through 1K,Collector is to +12 with pullup of 1K, Emitter is to GND.

Then either the SSR is Miss-marked or it is defective.

I have driven dozens of SSRs with 3v to 5v inputs from micro-controllers, and never had a problem turning the SSR on & off.

Something is amiss!

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Sounds like the OC1A pin may have been configured as an input, so no drive capability.