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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
 Posted - Mar 18 2014 : 08:35:14 AM
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While the battery is charging, Q2 is turned off. As the battery voltage rises, so also does the pot wiper. When the wiper voltage reaches about 6.4V (D3 + Q2 gate voltage drop) Q2 will turn on. That pulls down the triac gate voltage and stops it turning on.
So R2 is set so its wiper voltage is about 6.4V when the battery is charged to 13.8V. So it controls the battery voltage at which the charger stops charging. |
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Aaron Cake
Administrator
Canada
6717 Posts |
Posted - Mar 18 2014 : 10:02:00 AM
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You're making arbitrary changes to the circuit so it's no wonder it doesn't work.
Follow the instructions on the page:
http://www.aaroncake.net/circuits/charger2.asp
Step 1 in the notes tells you how to adjust the circuit and as mentioned, there must be a battery (or equivalent load) at the output to do so. |
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 18 2014 : 1:11:17 PM
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If he fits the capacitor and then adjusts for charging voltage, he won't have to continuously monitor the battery voltage during its first time use.
It's a sensible addition that should have been included in the original circuit. |
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 19 2014 : 06:50:13 AM
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How can I prove that the battery is charging? Thank you pebe and aaron cake for helping. :)
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 19 2014 : 09:35:40 AM
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When charging, the LED will be lit very dimly - if at all.
When charged, the LED will be lit normally. |
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Aaron Cake
Administrator
Canada
6717 Posts |
Posted - Mar 19 2014 : 09:45:56 AM
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quote:
Originally posted by kaycee
How can I prove that the battery is charging? Thank you pebe and aaron cake for helping. :)
Measure the voltage. It should rise slowly. |
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 24 2014 : 10:14:07 AM
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I already made the circuit in the pcb, the output of the original circuit is 9 something but when i put 100uF cap across the output, it is 13 something. How did this happened? How will I explain that the input is only 12V but the output is 13V??
Also,the LED doesn't light. When will the LED turn on? Thank you again. Thank you very much.:))
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 24 2014 : 12:13:42 PM
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The peak voltage of your transformer is 1.4 x 12VRMS = 16.8V. So allowing for the voltage drop of D1 and Q1, the voltage your reading is pretty much what I would expect.
Re the LED not lighting. Short out anode and cathode of Q2 to ensure that the LED is workjng correctly. If OK, look again at my post of March 19. It's not lit because Q1 is still trying to charge the cap. Have you adjusted R2 correctly? Turn R2 so its slider goes toward the end that's connected to R1, then wait a few seconds for the cap to discharge. Will the LED now light. If not, measure the voltage across the 100µF cap. What is that voltage?
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 25 2014 : 05:49:54 AM
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I dont know when to adjust R2. :(
I will short out the anode and cathode of Q2 and i will turn on the charger connected to the 220V?
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 25 2014 : 06:24:32 AM
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I already shorted the anode and cathode, the LED blinked only.
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 25 2014 : 07:24:45 AM
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| The LED should not just blink. It should stay lit as long as you are shorting the bottom end of R6 to ground. Does it? |
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 25 2014 : 09:28:48 AM
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| I thought you said I'm going to short anode and cathode of Q2? Am I supposed to short that or not? Both end of R6 will be shorted and connect it to the ground? |
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 25 2014 : 10:39:35 AM
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Ignore what I said about R6. I did not have the circuit in front of me when I replied, and I assumed that R6 connected to Q2 anode, but it does not.
Short out anode and cathode of Q2 as I said before. The LED should stay lit as long as you keep them shorted. |
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kaycee
Apprentece
Philippines
19 Posts |
Posted - Mar 25 2014 : 10:51:23 AM
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| what will i do if the LED does not light? |
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Mar 25 2014 : 12:38:43 PM
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| Does it light? |
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12V Battery Charger
