Portable iPOD MP3 Player Charger with MC34063A

Portable iPod charger that you can use while abroad from your computer. The ambit is based about an MC34063 switchmode regulator. This has aerial ability so that there is actual little calefaction produced central the box, alike back carrying its best achievement current. The ambit is added complicated than if we acclimated a 7805 3-terminal regulator but back the ascribe voltage could be 15V DC or more, the voltage amusement in such a regulator could be 5W or added at 500mA. and 5W is far too abundant for a 7805, alike with absolutely a ample heatsink.

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LM317 Battery Charger Circuit

LM317 Battery Charger Circuit

There are abounding circuits accessible for charging batteries, but abounding are for NiCd or NiMH batteries. They will not assignment for lead/acide batteries, so don’t use these!!! The best way to allegation a array is with a accepted bound voltage regulator. This sets a best accepted (say 1A) that will breeze to allegation the battery. If the accepted rises over this set current, the regulator will be affected to put out a lower voltage. Since voltage drops, so will the current; appropriately accepted limited. While the array is charging, the accepted should abatement boring while voltage starts to increase. In the end the accepted will be abutting to aught and the voltage will be according to the set voltage.

Use the afterward to architecture a charger:

1) The charging accepted should be kept to about 0.1 times the accommodation of the battery. So a 10Ah array should be answerable with 1A of accepted (10 x 0.1 = 1). The array will not be affected (quick charged) this way and assures a best lifetime.

2) The charging voltage should be set to 2.3 - 2.4V per 2V cell. So a 12V array (6 beef of 2V) is answerable at 6 x 2.3 = 13.8V.

3) The agent ambagious for the charger accumulation is called at the charging voltage additional 3V regulator bead additional 1.4V rectifier bead (two diodes) additional 10% safety. So for a 2V battery, the ambagious (AC) is 2V + 3V + 0.7V + 0.7V = 6.4V + 10% = 7V.

4) The charging accepted is bound by the baby resistor in the accepted leg of the charger. The amount for this resistor can be affected with: R = 0.6V / max current. So if I appetite a best accepted of 0.5A, I will charge 0.6V / 0.5A = 1.2 ohms. The 0.6V is the voltage appropriate for the transistor to go absolutely into conduction. Between 0V and 0.6V the transistor will acclimatize the regulator to access or abatement voltage depending on the accepted it is passing.

5) The charging voltage can be set application the potentiometer. Just angle up a volt-meter to the charger (without the array attached) and acclimatize the achievement voltage until it macthes the charging voltage. Use a 1K pot for 2V batteries, use 5K for 6V and 12V batteries.

6) Use an added agglutinate on the charger, about two times the best accepted you are charging with. Fusing is analytical for assurance reasons. A array can bear 100+ amperes during a short, so it can account austere accident or alike fires back article goes amiss with the charger. Put the agglutinate abaft the regulator in the advance activity to the battery. This agglutinate is not to assure the accumulation from a abbreviate in the charger, but to assure aggregate abroad from the array in case of a abbreviate anywhere. Don’t balloon to agglutinate the primary ambagious of the charger as well…

7) You’re set up to charge…

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Universal Battery Charger Schematic

The charger's output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-connected cells up to a maximum of 18V.

Power transistors Q1 and Q2 are connected as series regulators to control the battery charger's output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10.

As the charging voltage across the battery begins to drop, the current through R8 decrease. Then the voltage feeding pin 5 of U3 decreases, and the comparator output follows, turning Q3 back off, which completes the signal's circular path to regulate the battery's charging current.

The charging current can be set by adjusting R10 for the desired current. The circuit's output voltage is set by R9

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Li-ion Battery Charger with TL431

Li-ion Battery Charger with TL431

After a simple treatment can be omitted from the initial involvement thermistor to compensate for temperature dependence. After treatment (see Figure 1) works not as a transistor T4 voltage follower, but as a switch. If charging voltage is present, the transistor T4 is closed and the divider resistors R4 and R6 does not pass any current. Base-emitter transition T1 is polarized in the reverse, based on the zero voltage, so neither transistor T1 does not pass overhead stream. After connecting the charging voltage of at least 4.9 V is based on T1 will stress about 0.5 to 0.6 V greater than the battery voltage nabíjeného. When fully charged battery (4.2 V) is based on T1 approximately 4.7 V. Because the R input voltage stabilizer TL431 is approximately 2.5 V, the transistor T4 opened voltage around 2.2 V. At this voltage the transistor T4 open a channel is switched resistance of singles, more than tens of ohms and its resistance in the divider practically apply. If charged periodically discharged battery, the voltage on the basis of T1 and T4 is less need not be fully open. It does not matter, because at this stage the battery is charging in the same mode of constant current and voltage stabilization does not apply. For proper function of the charger must have transistor T4 low threshold voltage. Good matches transistor BSS138 (SMD) or BS108 for classical mounting. Both types have a threshold voltage of typically about 1 V. The device charging current with transistors T2 and T3 has been described in detail here and I will not repeat it here.

Charging voltage adjustment is no longer dependent on the threshold voltage of T4 and the thermistor resistance. Temperature stability is determined practically only the stability of IC1. It was therefore removed from involvement trimmer and charging voltage is set to fixed resistors R4 and R6. If you omit (shorts) resistor R5, the final charging voltage typically slightly larger than 4.2 V. The integration of resistor R5 can adjust the voltage to size. Just when you recharge the battery for 90 to 95%, we recommend setting the charging voltage from 4.1 to 4.15 V. The lower charging voltage is very significantly increases the number of charge cycles and prolonged battery life.

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