# Opto coupler

Discussion in 'Electronic Basics' started by lerameur, Jan 25, 2007.

1. ### lerameurGuest

hello,

I have bought the MCT6 chip (opto coupler)
I grounded pin 3 and 5

If I put a voltage a cross pin 4 should I get the same voltage across
pin 6 ??
I am not getting anything

k

2. ### lerameurGuest

I also put pin 6 to Vcc and a resistor to pin 5 to ground, and take
the voltage at pin 5 , but no luck either

k

3. ### John FieldsGuest

---
That's because you're hooking it up wrong.

You should be doing it like this: (View in Courier)

+5V>-+-------------+
| |
+--> | |
S1 | |
O |
| |
[360R] [2K5]
| |
| +------>VOUT
|3 |5
+--|--------|--+
| | | |
| | C |
|[LED]--> B |
| | E |
| | OPTO | |
+--|--------|--+
|4 |6
GND>------+--------+------>GND

Or like this:

+5V>-+-------------+
| |
+--> | |
S1 | |
O |
| |
[360R] |
| |
| |
|3 |5
+--|--------|--+
| | | |
| | C |
|[LED]--> B |
| | E |
| | OPTO | |
+--|--------|--+
|4 |6
| +------>VOUT
| |
| [10k]
| |
GND>------|--------+------>GND

In the first example, when S1 is open VOUT will be close to 5V and
when S1 is closed VOUT will be close to 0V (0.5V or something like
that).

In the second example, when S1 is open VOUT will be very close to 0V
and when it's closed VOUT will be close to 5V.

4. ### lerameurGuest

Thanks JF
This is a similar circuit found on one spec sheet.
I took a snapshop of the circuit and posted here:
http://www3.sympatico.ca/lerameur/

infortunately it still not working

ken

5. ### ChrisGuest

OK, lerameur. First off, you might want to look at the datasheet:

http://www.nteinc.com/specs/3000to3099/pdf/nte3086.pdf

Also, your picture shows that the MCT6 collector is connected to GND
through the 10K resistor, and your emitter is connected to +5V. Switch
those two and it should work, unless you let out the magic smoke

It's always a good idea to look at the datasheet before you plug it in.
;-)

Cheers
Chris

6. ### lerameurGuest

I also switch the cathode and anode from the diagram shown.

7. ### ehsjrGuest

Right. You need to have pin 3 and pin 5 connected to ground.
You need pin 6 connected to the 10K resistor - the other end
of the resistor goes to (+). (Might be a 1K resistor - I
can't tell if that is a red or an orange band)
The other resistor connects from pin 4 to +5 volts, but
I'd change it to 220 ohms.

Ed

8. ### lerameurGuest

Ok great its working, thank you