Asked
— Edited
Alright. My dewy build is almost finished, but I have hit a problem with the relays I'm using. They require at least 1.5v to activate them, and then nothing to deactivate them.
Using a set digital control, I can turn them on, but turning the control off doesn't deactivate the relays.
Why would this be? Does setting the digital port off not set the voltage low?
How else can I activate them and deactivate them with the ez-b if not in this manor?
Can't find the thread(s), but this has been seen before. I think the solution was to use a pull down resistor, but I am not positive (nor do I know how that would be wired).
Alan
Hi @MazeHorizonTech, I have an 8 relay board which I run off my ezb. I had tried many different ways to operate the relays directly from the ezb port, but had the problem you are having. The way I cured it was to build a TIP 120 transistor board and used it as a slave. Rich made a post a while back on how to build the circuit. I will post the location shortly. Ron
I got lucky and found it quick, : https://synthiam.com/Community/Questions/3050
I made up a few different styles and used one to drive a remote control for a set of wireless 110 volt sockets. I use voice commands to operate the lights and coffee maker.
The problem with the tip120 is it is essentially a relay to run a relay, and it just seems like a waste to me.
Could a pull down resistor do it? I'm not sure how it could be wired either. Mainly it is just getting the voltage low enough to disable the relay. Why it stays high I do not know...
I agree, but it works. Maybe some else can help. Rich and Richard R gave feedback on this subject but I forget what they said.
Richard R linked to some relays that work out of the box with the EZ-B (I thought I bookmarked that but can't seem to find it today either). The thread where he mentioned it most recently also had the information about the pull down resistors I believe.
Alan
Here is a thread with same problem but different solution than I was recalling. https://synthiam.com/Community/Questions/6604
@MazeHorizonTech, @AndyRoid: Alan pointed to the post with correct solution.
To summarize your relay needs a 5v logic to operate (I have a few i got from ebay) it works with Arduino (5V logic), but does not work with a RPI/EZB because the logic level is 3.3v, not enough to trigger the Relay logic.
TIP120 can work but is old, and is not an efficient component.
you need a Logic Level circuit i'm familiar with these:
http://www.ebay.com/itm/IIC-I2C-Logic-Level-Converter-Bi-Directional-Module-5V-to-3-3V-For-Arduino-/121868205078
https://www.sparkfun.com/products/12009
https://www.adafruit.com/products/395
http://www.digikey.com/product-detail/en/texas-instruments/SN74HCT245N/296-1612-5-ND/277258
the first 3 are bi-directional the last one only converts from 3.3 to 5v.
you will need also a 5v to source the circuits