Question: Choosing/Using an SSR

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I'm working on a circuit to replace a wired remote control unit with
an RF remote. The existing remote is nothing more than 3 push buttons
that connect a 5V supply voltage to ground via a 470 ohm resistor
(remote connected via some RJ-11 connectors and a phone cord. The
buttons are UP count, Down Count, and Reset.

I'm having some trouble interfacing the RF remote circuitry with the
wired remote interface. My plan is to use 3 SSR's in place of the
existing push button switches. The RF remote works great, and lights
up test LED's just as I would expect when push buttons on the
transmitter are pushed. My next step was to replace the LED's with
the SSRs. I chose the SHARP PR22MA11NTZF to do the job. I connected
pin 2 to ground, and 1 to my output. Then I hooked up pin 6 and 4 to
my continuity tester and hit the buttons on my transmitter.
Everything looked like it was going smoothly. The SSR was behaving
just like the switch. When I held the buttons down, I got a solid
buzz, when i hit them fast, i got short blips. Then I replaced the
continuity tester with the wires I wanted to short (+5V from the
circuit i am driving, and Gnd (via a 470 ohm resistor).

Here is where my problem was noticable. I push the button one time,
it latches the SSR, causes the circuit to count as expected, but then
never unlatches, so even after i release the button my circuit keeps
counting. I'm assuming I have either chosen the wrong SSR, or need
different circuitry somewhere as it behaves as if the current flowing
through the SSR after the initial button press is holding the switch
on, when I want it to turn off when the drive logic turns off.

Any ideas? If someone could point me in the right direction for a
more appropriate SSR, or SSR circuitry that would be great. Thank you
in advance for any assistance you can provide.

 

[John Popelish]

I'm having some trouble interfacing the RF remote circuitry with the
wired remote interface. My plan is to use 3 SSR's in place of the
existing push button switches. The RF remote works great, and lights
up test LED's just as I would expect when push buttons on the
transmitter are pushed. My next step was to replace the LED's with
the SSRs. I chose the SHARP PR22MA11NTZF to do the job. I connected
pin 2 to ground, and 1 to my output. Then I hooked up pin 6 and 4 to
my continuity tester and hit the buttons on my transmitter.
Everything looked like it was going smoothly. The SSR was behaving
just like the switch. When I held the buttons down, I got a solid
buzz, when i hit them fast, i got short blips. Then I replaced the
continuity tester with the wires I wanted to short (+5V from the
circuit i am driving, and Gnd (via a 470 ohm resistor).

This relay is intended for AC loads. Its output device is a
latching thyristor that relies on the current zero crossing
twice per AC cycle to reset it to a nonconducting state.
http://document.sharpsma.com/files/pr22ma11_e.pdf

Your test meter does not draw enough current for the
thyristor to latch on, but your intended load does.

You need an SSR intended for DC loads (mosfet output or
photo transistor) If your load current is a few
milliamperes, you may get by with an ordinary opto isolator
like one of these:
http://rocky.digikey.com/WebLib/Toshiba/Web Data/TLP331,332.pdf

 

[John Fields]

I'm working on a circuit to replace a wired remote control unit with
an RF remote. The existing remote is nothing more than 3 push buttons
that connect a 5V supply voltage to ground via a 470 ohm resistor
(remote connected via some RJ-11 connectors and a phone cord. The
buttons are UP count, Down Count, and Reset.

I'm having some trouble interfacing the RF remote circuitry with the
wired remote interface. My plan is to use 3 SSR's in place of the
existing push button switches. The RF remote works great, and lights
up test LED's just as I would expect when push buttons on the
transmitter are pushed. My next step was to replace the LED's with
the SSRs. I chose the SHARP PR22MA11NTZF to do the job. I connected
pin 2 to ground, and 1 to my output. Then I hooked up pin 6 and 4 to
my continuity tester and hit the buttons on my transmitter.
Everything looked like it was going smoothly. The SSR was behaving
just like the switch. When I held the buttons down, I got a solid
buzz, when i hit them fast, i got short blips. Then I replaced the
continuity tester with the wires I wanted to short (+5V from the
circuit i am driving, and Gnd (via a 470 ohm resistor).

Here is where my problem was noticable. I push the button one time,
it latches the SSR, causes the circuit to count as expected, but then
never unlatches, so even after i release the button my circuit keeps
counting. I'm assuming I have either chosen the wrong SSR, or need
different circuitry somewhere as it behaves as if the current flowing
through the SSR after the initial button press is holding the switch
on, when I want it to turn off when the drive logic turns off.

Any ideas? If someone could point me in the right direction for a
more appropriate SSR, or SSR circuitry that would be great. Thank you
in advance for any assistance you can provide.

 

[John Fields]

---
If, instead of just describing your circuit verbally, you could also
post a schematic somewhere, (alt.binaries,schematics.electronic
would work) then we wouldn't have to guess about what "solid buzz"
and "my circuit keeps counting" means.

 

[Jamie]

I'm working on a circuit to replace a wired remote control unit with
an RF remote. The existing remote is nothing more than 3 push buttons
that connect a 5V supply voltage to ground via a 470 ohm resistor
(remote connected via some RJ-11 connectors and a phone cord. The
buttons are UP count, Down Count, and Reset.

I'm having some trouble interfacing the RF remote circuitry with the
wired remote interface. My plan is to use 3 SSR's in place of the
existing push button switches. The RF remote works great, and lights
up test LED's just as I would expect when push buttons on the
transmitter are pushed. My next step was to replace the LED's with
the SSRs. I chose the SHARP PR22MA11NTZF to do the job. I connected
pin 2 to ground, and 1 to my output. Then I hooked up pin 6 and 4 to
my continuity tester and hit the buttons on my transmitter.
Everything looked like it was going smoothly. The SSR was behaving
just like the switch. When I held the buttons down, I got a solid
buzz, when i hit them fast, i got short blips. Then I replaced the
continuity tester with the wires I wanted to short (+5V from the
circuit i am driving, and Gnd (via a 470 ohm resistor).

Here is where my problem was noticable. I push the button one time,
it latches the SSR, causes the circuit to count as expected, but then
never unlatches, so even after i release the button my circuit keeps
counting. I'm assuming I have either chosen the wrong SSR, or need
different circuitry somewhere as it behaves as if the current flowing
through the SSR after the initial button press is holding the switch
on, when I want it to turn off when the drive logic turns off.

Any ideas? If someone could point me in the right direction for a
more appropriate SSR, or SSR circuitry that would be great. Thank you
in advance for any assistance you can provide.

That's how they work.
once current is moving through the SSR's, they stay latched until the
current drops below the holding point.
if you're dealing with DC volts, use logic type fets.