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[Reply #30 on:]

I see how you got confused. Notice they are biasing the phototransistor to switch faster rather than act more linearly. I don't know what the purpose of the Olimex circuit is. It's an optically coupled OR-gate that resets the processor for whatever reason I don't know.

Not quite. It's poorly drawn. Note that each opto collector has a I1, I2, I3, or I4 label. These wire over to digital input pins on the processor chip.

lol, no I mean the schematic posted with reply #26.

[Reply #31 on:]

so, my question in reply 26, will it work?

[Reply #32 on:]

so, my question in reply 26, will it work?

Is you intent still to energize the relay with a LOW on INx?

[Reply #33 on:]

so, my question in reply 26, will it work?

Is you intent still to energize the relay with a LOW on INx?

If so, you will use a circuit like http://www.ebay.com/itm/8-Channel-DC-5V-Relay-Module-for-Arduino-PIC-ARM-DSP-AVR-MSP430-TTL-Logic-/271188081780?pt=LH_DefaultDomain_0&hash=item3f2411bc74&autorefresh=true.

[Reply #34 on:]

To make this easy, I attached just one of my relay circuits.  This schematic, from what I can see, is the same as in the link that Papa posted, except for adding a LED (w/resistor) between GND and +5V.

[Reply #35 on:]

To make this easy, I attached just one of my relay circuits.  This schematic, from what I can see, is the same as in the link that Papa posted, except for adding a LED (w/resistor) between GND and +5V.

No, more like this.

[Reply #36 on:]

To make this easy, I attached just one of my relay circuits.  This schematic, from what I can see, is the same as in the link that Papa posted, except for adding a LED (w/resistor) between GND and +5V.

No, more like this.

Yes, that is a proper interface from opto to relay switching transistor. I would not bother with having two visual leds performing the same function, I would eliminate the opto input led indicator and adjust it's series resistor to compensate for it's elimination.

Lefty

[Reply #37 on:]

Instead of using 8 Arduino pins to drive your board, why no use one a single 74HC595 between the arduino and the optocouplers?

This way you'll use only 3 arduino pins, instead of 8, and the complexity added to your design will be minimal (and a 595 is pretty cheap).

[Reply #38 on:]

Yes, that is a proper interface from opto to relay switching transistor. I would not bother with having two visual leds performing the same function, I would eliminate the opto input led indicator and adjust it's series resistor to compensate for it's elimination.

Lefty

Wow, I just noticed the LEDs..  You're right.  I will have to change my design for the relay LED.  I wanted the LED to light when the relay has power (Not switched on).  The LED on the opto would light when the relay switched on.  It's not really a necessity to have either LED, but I like seeing the lights.  Besides, I have hundreds of 1206 LEDs in a variety of colors..

Thanks Retro and Papa.  Just to let you know Papa, I knew how transistors worked, but the symbols stumped me for some reason.  Last night (late), it finally sunk in.  So, +1 to ya both.

Instead of using 8 Arduino pins to drive your board, why no use one a single 74HC595 between the arduino and the optocouplers?

This way you'll use only 3 arduino pins, instead of 8, and the complexity added to your design will be minimal (and a 595 is pretty cheap).

Good idea, have quite a few of those in SMD that I have been wanting to use.

[Reply #39 on:]

Thanks Retro and Papa.  Just to let you know Papa, I knew how transistors worked, but the symbols stumped me for some reason.  Last night (late), it finally sunk in.  So, +1 to ya both.

Thanks, codlink, I knew you'd get it if you thought about it long enough.