Hi there,
I've got a wireless doorbell that runs on 3 C size batteries (i.e. 3 x 1.5V). Here is the product:
http://www.masters.com.au/product/902290351/hpm-wireless-door-chime
I measured the DC in circuit, and it showed 4.8V.
I had a spare 5V 2A wall wart lying around, so I thought it would be a nice way to power the doorbell unit, since it was quite fussy about batteries losing charge (would no longer make sound as soon as the batteries lost a bit of charge). I saw some 'battery eliminator' projects on the net, that showed how to do this in a nice way.
The wall wart measured at 5.6V, so I added a diode to drop the voltage. In the doorbell circuit, the measured DC voltage was then 4.8V, exactly like it was when running on batteries.
I tried some tests using both buzzers, but the doorbell unit did not make any sound. As a sanity check, I reinserted the batteries, and then tried the tests again. Yep, there was plenty of ringing (my wife thought someone was playing pranks outside with out doorbell!!!).
I'm a newbie, and this has got me wondering. How can the circuit tell the difference between the batteries and the wall wart, when they both give 4.8V. I'm thinking that 2A current should be easily enough, but I'm only guessing.
Any ideas?
Thanks!
Pete
I've got a wireless doorbell that runs on 3 C size batteries (i.e. 3 x 1.5V). Here is the product:
http://www.masters.com.au/product/902290351/hpm-wireless-door-chime
I measured the DC in circuit, and it showed 4.8V.
I had a spare 5V 2A wall wart lying around, so I thought it would be a nice way to power the doorbell unit, since it was quite fussy about batteries losing charge (would no longer make sound as soon as the batteries lost a bit of charge). I saw some 'battery eliminator' projects on the net, that showed how to do this in a nice way.
The wall wart measured at 5.6V, so I added a diode to drop the voltage. In the doorbell circuit, the measured DC voltage was then 4.8V, exactly like it was when running on batteries.
I tried some tests using both buzzers, but the doorbell unit did not make any sound. As a sanity check, I reinserted the batteries, and then tried the tests again. Yep, there was plenty of ringing (my wife thought someone was playing pranks outside with out doorbell!!!).
I'm a newbie, and this has got me wondering. How can the circuit tell the difference between the batteries and the wall wart, when they both give 4.8V. I'm thinking that 2A current should be easily enough, but I'm only guessing.
Any ideas?
Thanks!
Pete