Diodes Question

I am using some diodes in a project that incorporates small vibrating motors. The strange thing is when I measure the voltage (without hooking up the motors) if measure just before the diode the voltage is correct 5V when i measure after the diode te voltage appears 6.5V! how is this possible? i would expect a drop in voltage not a raise!
any ideas why?

Can you explain (tough without a diagramme) how the psu and diode is wired, and where you're measuring the voltage etc.?

Probably inductive kickback. That’ll get you in inductive circuits like relays, solenoids, and motors. Probably nothing to worry about if you have a diode in there. Many people choose to put a diode across the device in order to shunt any kickback.


Well, he mentioned motors, and anything with a core and lots of turns of wire tend to produce kickback when the field collapses. Although I haven't personally tried getting kickback from a motor, I have seen it first hand from relays and solenoids.

A waveform from a 'scope would be a great help at this point. That'll let us know right way where the 6.5V is coming from.


I am sorry for my late reply I am coming back with a proper schematic in a while thnx guys!

I take power from an Arduino Diecimila. My diode is a 1N4001 1A/50V. When I measure the voltage of arduino then (A circuit) I get 4.99 V. When I create a circuit like the B then the reading in my meter is around 6.3 V.

a multimeter: UNI-T UT30B :-/

the Arduino is working properly and I am taking power from a USB I am going to try what u suggest

I did use a resistor 9K ohms in parallel with the meter and I measure 4.45V

Thanx Richard it drove me crazy that thing especialy since it was showing an extra 2 Volts :-) I am in the middle of project with a quite tight deadline and I have to tackle all sort of things and that was in the middle of everything totally absurd! thanx again!