Hi,
I've been reading round my issue for a while now, I'm hoping you can confirm or argue my theory, and help with suggestions for resolution.
I have the PICAXE-20 Project Board and a couple of these relays on outputs from the Darlington driver: http://www.picaxestore.com/index.php/en_gb/electronic-components/relays-and-solenoids/rel002.html
The relays will be switched on independently (and only one at a time), to switch a separate simple circuit of 4.8V battery pack and motor.
Using the battery pack from the project board (3 * 1.5V) directly on the relays, they work fine.
But running through the project board I get a much quieter (barely perceivable) click, and it seems to disconnect one of the NC connections but not engage either NO connections. I'm not an electronics engineer, hope that makes sense.
Looking at the datasheet for the relay here: http://www.rapidonline.com/pdf/60-0405.pdf
It says the pull in voltage is 75%. I'm assuming this is 75% of the 6V rating, so my theory goes that they work fine directly with the 4.5V, but once hooked up to the picaxe, the voltage use from the rest of the system is reducing what's available to the relays. Does that make sense?
The datasheet also says nominal current is 75mA, I think I read somewhere that the Darlington driver is sinking 500mA, is that right? Could that be an issue?
Looking through the forum, most other folk seem to be working with 5V relays.
Any other thoughts on reasons the relays aren't working?
Ideally I'd like to run the picaxe on three rechargeable batteries, so 3.6V.
So, if my theory is correct, I guess there are two resolutions:
I'm erring towards the second option. Any thoughts?
Can anyone suggest a better resolution?
Many thanks for your time, sorry for so many questions all in one post.
Cheers, siden.
I've been reading round my issue for a while now, I'm hoping you can confirm or argue my theory, and help with suggestions for resolution.
I have the PICAXE-20 Project Board and a couple of these relays on outputs from the Darlington driver: http://www.picaxestore.com/index.php/en_gb/electronic-components/relays-and-solenoids/rel002.html
The relays will be switched on independently (and only one at a time), to switch a separate simple circuit of 4.8V battery pack and motor.
Using the battery pack from the project board (3 * 1.5V) directly on the relays, they work fine.
But running through the project board I get a much quieter (barely perceivable) click, and it seems to disconnect one of the NC connections but not engage either NO connections. I'm not an electronics engineer, hope that makes sense.
Looking at the datasheet for the relay here: http://www.rapidonline.com/pdf/60-0405.pdf
It says the pull in voltage is 75%. I'm assuming this is 75% of the 6V rating, so my theory goes that they work fine directly with the 4.5V, but once hooked up to the picaxe, the voltage use from the rest of the system is reducing what's available to the relays. Does that make sense?
The datasheet also says nominal current is 75mA, I think I read somewhere that the Darlington driver is sinking 500mA, is that right? Could that be an issue?
Looking through the forum, most other folk seem to be working with 5V relays.
Any other thoughts on reasons the relays aren't working?
Ideally I'd like to run the picaxe on three rechargeable batteries, so 3.6V.
So, if my theory is correct, I guess there are two resolutions:
- Give more power, I could run the board off four rechargeable AA batteries to give 4.8V and hope
- Change the relays out some requiring less switching power, can anyone suggest a suitable DPDT relay?
I'm erring towards the second option. Any thoughts?
Can anyone suggest a better resolution?
Many thanks for your time, sorry for so many questions all in one post.
Cheers, siden.