I read on the forum that I can treat the Adafruit Latching Mini Relay FeatherWing as a SPDT switch.
How quickly can this relay switch?
I'm looking for something that handle switching over the range of 4Hz to 12Hz.
FeatherWing relays response time
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- Claude_J_Greengrass
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- westfw
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Re: FeatherWing relays response time
Mechanical relays tend to have a maximum number of switching cycles (buried somewhere in the datasheet, if you have an actual full datasheet for the relay)
It's not awful (a representative datasheet I looked up on digikey said 20k to 100k cycles, but it's probably not the sort of thing where you want to be switching several times a second, either. (heh. Similar to the EEPROM in an AVR.)
The same datasheet says activation/turn-off times are around 5ms, but I'm not entirely sure exactly what that means. Don't forget that a relay coil is a sizeable inductor, so rapidly changing the current in the coil can be ... challenging.
It's not awful (a representative datasheet I looked up on digikey said 20k to 100k cycles, but it's probably not the sort of thing where you want to be switching several times a second, either. (heh. Similar to the EEPROM in an AVR.)
The same datasheet says activation/turn-off times are around 5ms, but I'm not entirely sure exactly what that means. Don't forget that a relay coil is a sizeable inductor, so rapidly changing the current in the coil can be ... challenging.
- adafruit_support_bill
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Re: FeatherWing relays response time
Switching a mechanical relay at 4Hz or more is not practical for several reasons:
* It would be noisy as heck
* It probably would not survive more than a day or two
* As an inductive load, it would create a ton of EMI
Better to look for a solid-state relay. Or, for a DC load, you could use a MOSFET: https://www.adafruit.com/product/355
* It would be noisy as heck
* It probably would not survive more than a day or two
* As an inductive load, it would create a ton of EMI
Better to look for a solid-state relay. Or, for a DC load, you could use a MOSFET: https://www.adafruit.com/product/355
- Claude_J_Greengrass
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Re: FeatherWing relays response time
I originally used Solid State Relays (SSR) for the switching. They require 5v input to switch. That was OK when I was developing on a Mega2560. For various reasons, I switched to the PyGamer and a couple of 3.5v relays. But as you say, too slow and they will burnout.
I have read that 5.0v SSR can be switched by 3.5v from the PyGamer but I haven't tested it. The PyGamer offers so much but unless I can solve my switching problem I may have to move to a different microcontroller board.
I need to switch 50v to 60v at a few miliamps at between 4Hz and 12Hz. Any alternatives?
I have read that 5.0v SSR can be switched by 3.5v from the PyGamer but I haven't tested it. The PyGamer offers so much but unless I can solve my switching problem I may have to move to a different microcontroller board.
I need to switch 50v to 60v at a few miliamps at between 4Hz and 12Hz. Any alternatives?
- adafruit_support_bill
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Re: FeatherWing relays response time
If you have an SSR that works for your application, you can use a level-shifter or even a simple transistor circuit to boost the 3.3v logic to 5v to drive it.
- Claude_J_Greengrass
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Re: FeatherWing relays response time
My experience with h/w is very out of date. List h/w I worked on have ICs with 4 Nan gates on a chip.
Can you please expand on "level shifter" hardware. thx
Can you please expand on "level shifter" hardware. thx
- adafruit_support_bill
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Re: FeatherWing relays response time
Here is one: https://www.adafruit.com/product/1875
You provide 3.3v to the "A" side and 5v to the "B" side. Then 3.3v signals connected to one of the A side pins get shifted to 5v on the corresponding B side pin.
You provide 3.3v to the "A" side and 5v to the "B" side. Then 3.3v signals connected to one of the A side pins get shifted to 5v on the corresponding B side pin.
- Claude_J_Greengrass
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- Joined: Sat Jul 24, 2021 10:53 am
Re: FeatherWing relays response time
Thanks for the headsup on the level shifter.
Please be positive and constructive with your questions and comments.