|02-24-2003, 10:11 AM||#21|
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Dennis, I just drove right by your area last Monday on my way back from Southampton where my brother lives, so on one of my trips, I can also stop in to help you out with this trickle charger if necessary.
May I ask the following:
Do you have a voltmeter, and know how to use it?
Do you know anything about electronics? The reason I ask this is to know where to start. Ohms law?, etc.
I use deans connectors for all connections to receiver batteries. (my own standard). I also use Radio Shack connectors (coaxial). Their part number is not right at hand, but I will try and get that for you.
My trickle charger is set up with one 20 volt (or so) output. The actual voltage output is not critical, as long as the system can handle say, 500 milliamps or more. A 12 volt charger is OK, but I prefer a somewhat higher voltage. I built my own rectifier (transformer, ac to DC converter, capacitor). The transformer was a 24 volt AC output, rectified and filtered to a 20 volt DC output.
I like to set the trickle charge on a receiver 4.8 volt battery at about 5.2 volts. If it's a 600 milliamp pack, then 1/50th of that is 12 milliamps.
My 20 volts from the supply must then drop the difference (20 - 5.2 = 14.14.8 volts at 12 milliamps. A resistor of proper value, connected in series with the 4.8 volt battery, is all I need. The voltage drop across the battery cannot be controlled, so I must control the voltage drop across the resistor.
Ohms law says voltage is equal to current times resistance. If the voltage across the resistor is 14.8 volts, and the current through it is 12.8 milliamps (.012 amps), the 14.8 divided by .012 is equal to 1233 ohms. The 1233 ohms is then the value of the resistor to be used in series with the 4.8 volt 600 ma pack..
If this sounds complicated, let me know, and I'll make up a diagram and mail it to you, or scan it and send it. Like anything else, if you have done it, it's easy. It's only difficult when you don't know!
I also have a meter that I use to measure current. Some multimeters are capable of measuring current, but you have to be careful not te exzceed the maximum rating. This meter must be connected in series to measure current.
If you send me your phone number, I can call you after 8 PM any night, or on a weekend. No limit on my long distance time after 8PM.
Don't be intimidated by all these numbers. It's not that difficult. Hope to hear from you soon. My e-mail is "email@example.com"
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