Why didn't I get the voltage drop expected on diode rectifier?

[red913]

I got some 1N4001 diodes and putting 3 in series gave me a voltage drop of about only .4V. I don't understand why I didn't get more? I need about 3V drop. I'm not quite sure what to look for on the data sheet either. If someone could direct me in what I did wrong or direct me to the proper diode(I think the one I ordered may be incorrect) I would be very grateful.

 

[godfreyl]

3 in series gave me a voltage drop of about only .4V

That doesn't sound right. How did you measure? what is the current through the diodes?

 

[red913]

Power goes to the first diode diode and then I put the meter on the end of the third diode connected in series and the other end of the meter to ground. Also the motor itself runs a lot harder. I don't have anything to measure the current right now. Of course now that I think about it the motor running harder could be the new wall plug in power supply I have. It runs at 3A vs my previous method of power which was just 4 AA batteries.

 

[godfreyl]

Power goes to the first diode diode and then I put the meter on the end of the third diode connected in series and the other end of the meter to ground.

What you're describing sounds like this:



But that doesn't make any sense. Can you explain a bit more? What's the motor connected to? Are the diodes supposed to be in series with the motor, or what?

 

[udhay_cit]

I think you are measuring the voltage with open circuit.....


The circuit will work as you expected when it has a closed path.....