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Thread ID: 97972	2009-03-06 03:04:00	Calling electronics experts	pcuser42 (130)	PC World Chat

Post ID	Timestamp	Content	User
753883	2009-03-08 20:59:00	I'm using rechargables for this, as the original idea was that I wouldn't need regulators, as 1.2v*4=4.8, just enough for USB (5v with a 5% tolerance). However, my NiMH batteries give out not 1.2v, but 1.35v! :annoyed: This comes out to 5.4v, which is too high. It is higher because you are not using them and a voltmeter presents a very tiny load. When they are connected to a real circuit and doing some proper work the voltage will drop	Agent_24 (57)
753884	2009-03-08 21:05:00	not all nihms are that high are they?....... or doesnt the 1800 2400 stuff affect the voltage You will notice these numbers are in mAh (which refers to milliampere-hours)and it is a measure of how much current the battery is able to supply over an hour and it is used as an indication of how much capacity the battery has. The higher the mAh rating, the longer the battery will last.	Agent_24 (57)
753885	2009-03-09 01:22:00	yep either a silicon diode or a 5 volt zener diode with a small enough resistor to not smoke the zener or the device, 100 ohm may do nicely, with zener diodes the stripe hooks up to the positive (resistor coming off the batteries positive side) and non striped directly to negitive, this will drop the voltage to a suitable level and if you use unregulated supplies will reduce the peak voltages, with rechargable MP3/4 players etc you will need a short circuit or low value resistor on the negative side data line (eg the data line closest to the negative power rail) this will tell the MP3/4 to start charging	williamF (115)
753886	2009-03-10 08:19:00	There are USB plugpacks all over the place that put out more than 5.4V. Any USB device should be able to handle 5.4V. If it's for an MP3 player it would be getting regulated down anyway to charge the battery etc.	george12 (7)
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