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.
How do you say it's poorly drawn?
retrolefty:
[quote author=Papa G link=topic=160464.msg1201554#msg1201554 date=1365991113]
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.
[/quote]
lol, no I mean the schematic posted with reply #26.
so, my question in reply 26, will it work?
codlink:
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.
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.
codlink:
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
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).
retrolefty:
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.
AlxDroidDev:
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.
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.
Well, I finally got around to assembling the relay board and guess what? It doesn't work.. No LEDs, nothing. When the 24V is connected I am getting ~21V on the Arduino input pins..
If anyone could take a look at my Eagle files, would appreciate any insight.
Relay Board Simple.brd (176 KB)
Relay Board Simple.sch (989 KB)
What is Vcc connected to?
What do IN1-IN5 connect to?
CrossRoads:
What is Vcc connected to?
Vcc is 24V supply. Now that I am looking closer, do I have Vcc and +5V backwards?
What do IN1-IN5 connect to?
IN1-8 are Arduino inputs to activate the optos.
From the marking on the relays, they appear to have 5V coils also.
Maybe 5V on both sides.
I see your point. It's getting late here so I will try tomorrow doing some more troubleshooting.
Thanks Crossroads. +1
Did some more testing and you're right. After I hooked it up the right way it worked.. But now I have a problem with relays 4, 6, 7, and 8. They do nothing. Going to check my soldering tomorrow.
I do have some revisions for the board to make it easier to assemble though, but really only cosmetic..
Thanks to everyone