GTR2Fan wrote:Looking at the specs, it does clearly state '3.5 V-12V to TTL control signal'. Expecting it to switch reliably at 3.3V is expecting it to reliably work out of spec if I'm interpreting the data correctly. It's often difficult to interpret specs when they're not written in correct English.
Hi
Actually there are several variations within that same designation.
It is a 5v Songle relay.
Some suppliers have placed it onto a PCB and added an optocoupler.
1. 5V relay
2. can be use for MCU
3. TTL control signal is 5V-12V
4. It can control AC or DC.can connect to 220VAC loader
5. one OP and one ON
6. power apply indicator
7. control indicator
OR
1, the new 5V Relay Module
2, can be used as microcontroller development board module can be used as home appliance control
3,5 V-12V to TTL control signal
4, the control signal DC or AC, 220V AC load can be controlled.
5, there is a normally open and one normally closed contact
6, a power indicator light
7, a control indicator, pull off, disconnect does not shine
8, transistor drive to increase the relay coil control pins high impedance.
9, the control pin has a pull-down circuit to prevent malfunction relay vacant
Note the 3rd line where it is looking like 3.5 v (3,5) but is actually 5v for the TTL value range.
So you pays your money and takes your choice (chance).