hi,

THis modified drawing was assuming a standard relay, but as 'brownout' states with that SSR it could be a direct drive from the 555 to the SSR.

I'll post the drawing for ref only.

The time constants 13K/100K and 100nF give an output freq from the 555 at 75Hz

Attached Thumbnails

 

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

 

I wonder if he needs to connect a resistor between the timer and SS relay? It's been a long time since I used those devices.

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

hi brownout.

These SSR's are 3 thru 32Vdc direct connection.

Why is he trying for a 37mSec sqr drive into relay?

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

 

hi dwhitt,

You do realise this SSR is intended for switching 'AC' on the output and not DC.???

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

 

I was thinking, if the input were an SCR or triac, he could be over driving it. But I trust your judgement on this one. It's probably something else.

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

The entire project is to test the timing of an actuator. I need the actuator to pulse on a 37msec square wave while the timer/counter counts the number of pulses. The actuator is driven from the output of the relay (AC).

So when everything is working - the square wave will go to the relay switching it on and off. The relay will then control the actuator turning it on and off in tiny pulses. The counter will count the number of pulses. The operator will run the actuator 20 degrees then check the number of pulses. It should be within a defined range in order to 'pass'. Then he/she will do the same in reverse or counter-clockwise.

So now, I just got back to my desk from the test bench. The problem is definitely with the SS Relay. I disconnected the relay and my o-scope showed me a beautiful, perfect 14.5V square wave. This was unexpected as I thought my input was only 6V so I checked the input and it too was 14.5V. So I am concluding that the relay is sucking some major amperage. Luckily, my chip didn't burn like the last 5 or 6.

I reconnected the relay and disconnected the timer and got the same 3V square wave as before. So the timer doesn't seem to add any to the problem.

This test was done without being connected to the actuator.

Still looking for help

 

My guess is that your relay is shot, or you've connected it incorrectly. What is the voltage of the actuator? Is it AC or DC?

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

The actuator os 115V, 400Hz

I have a backup relay so connecting another one up won't be a problem. I will try that and report back...

 

I think you're going to have another problem with your design. The data sheet says this relay is "zero switching." If I interpret that correctly, you will possible have as long as 1.25mS from the time you send the signal, until you have switching at the output. ( 800 zero crossings per second => 1.25mS between crossings )

You're error thus is: 1.25/37 = 33.8%

Also, the data sheet says the output is for 50/60 Hz. Not sure how well it will work @400Hz.

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

Oops, that should be 3.38% error. Sorry.

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

I think I could tweak out the switching delay on the chart. Right now I would just be happy with a working circuit.

Could you please direct me to the data sheet? I couldn't find anything in the data I was given abouut the frequency of the output. Thanks!

I changed out the relay and left the output open (not connected to the actuator or power supply). Turned it on and got a different waveform. It isn't right, but it is different. The wavelength was 4.5 µ seconds at about 4V. It spiked at around 7V.


What do you think?

Attached Thumbnails

 

 

I still don't understand why the output drops from 14.5V to 4V when the relay is connected. The spikes just look like inductive switching spikes to me. The datasheet is given below

Maybe someone else has an idea???W6225DSX1 DataSheet W6225DSX1 Pdf Download, - SeekDataSheet.Com

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

It is not an NE555, it is a low power TLC555 which is a Cmos one.

It has a 1k resistor in series with its power supply pin. Why???
Then its supply voltage jumps all over the place.

It might get hot when its supply was 12V because it might be a "factory reject" sold by RadioShack. Its max recommended supply voltage is 15V when it should be cold.

__________________
Uncle $crooge

 

Why indeed!? I missed that on the drawing.

__________________
You don't need a quadraphonic Blaupunkt -- you need a curve
ball.

 

hi dwhitt,
I deleted that resistor from the circuit I reposted.

Ref the +15V supply to your project, what is the source of the +15V.?

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/