Cai Webcontrol hooked up to the door buzzer (bell)

[siafu]

Hello all,

I have an intercom that when someone presses my button it rings in my home. I tested the voltage and while the button is pressed it reads approximately 3.5v. If I disconnect the actual bell or buzzer and press the button it reads just under 5v. So without load it's about 5 volts.

What I did, Is hook up one of the digital inputs on the Cai webcontrol to this buzzer signal, and have it programmed to email me each time someone presses the button. This works fine, get the email, the buzzer in my place makes the sound.

The problem is however, the sound level of the buzzer is very low, I would say about 75% less after I hooked up the CAi webcontrol into the mix. I tested the voltage and now the voltage is about 1.5v, this would explain why the buzzer sound is low.

How to get around this? What do I need to do and what parts do I need to have both the Cai Webcontrol and the buzzer hooked up at the same time and the buzzer sound to be louder?

Thank you for any input.

 

[CAI_Support]

Hi Siafu,

When you say the voltage is about 1.5V, is that the voltage before pressed the button or after button pressed? I assume that is after the button pressed.

WebControl TTL input has 10K pull down resistor. That should not drain much current. That resistor is to reduce any noise on line. You could add a 1k resistor between the TTL input and the button to see if that could reduce the current going into WebControl's TTL input.

It may worth to point out that both 3.5V and 5V are considered logic 1 by WebControl. Whatever the cause made input to 1.5V actually made it logic 0. I think you need to use couple resistors to divide the input voltage. For example, having two 1K resister in series, so that central point of those two resistors will be between 2.5V and 1.6V.

It sounds like your buzzer has a current limiting resistor in series. 10K pull-down resistor from WebConrtol actually considered big enough load to that current limiting resistor. If you use the pushbutton to cut off the ground for buzzer, then just connect the WebControl input across the switch, that may give you full range of logic 0 and 1.

Another way to do is to remove the pull down resistor from WebControl board. All the input pull-down resistors are on the bottom side of the PCB, easy to take one of them out.

CAI_Support

 

[siafu]

Hello Cai,

Voltage was measured when button is pressed in all tests mentioned above.

When button is not pressed, there is no voltage at all.

OK, will test with 1k resistor in line of TTL input and see if that helps. IF it helps a bit, then I would need a higher resistor, like maybe 10k?