voltage doubler and application

[rajaram04]

hello all

is the imge for voltage doubler is ok ?

is it applicable to designer a cell pjone charger with 3.7v battery followed by 5v zener etc ?

 

[d123]

Hi,

Not sure, just read circuit has several limitations, one being 555 current limit of 200mA; another being timer Vout is always 1 - 2V below V+ (3.7V * 2) - ~2V... - and the load influences that; also, charge diode-capacitor pumps are weak current-wise. I breadboarded a voltage inverter and a doubler with a timer and diode-caps months ago out of curiosity and I doubt I would use either in a real application, especially one that required more than a few mA, but each to their own preferences. Give it a go in a simulator or breadboard it and find out if it's suitable for the circuit needs. Have you seen the version using a complementary pair on the timer output? There's also a version that parallels two timers outputs to "double" the voltage.

 

[Audioguru]

A cell phone has a charger circuit in it that has a 5VDC USB input and charges the "3.7V" lithium battery cell to 4.20V. A voltage doubler is not used.
A 555 was used as a voltage doubler about 30 or 40 years ago. The voltage was not doubled, instead it was increased only a little.
A voltage boost converter circuit using a Mosfet and an inductor is used today, but not as a battery charger, it can be used to boost the 3.7V from a lithium battery cell in a power bank to the 5VDC USB used to feed the charger circuit in a cell phone.

 

[rajaram04]

Hi,

Not sure, just read circuit has several limitations, one being 555 current limit of 200mA; another being timer Vout is always 1 - 2V below V+ (3.7V * 2) - ~2V... - and the load influences that; also, charge diode-capacitor pumps are weak current-wise. I breadboarded a voltage inverter and a doubler with a timer and diode-caps months ago out of curiosity and I doubt I would use either in a real application, especially one that required more than a few mA, but each to their own preferences. Give it a go in a simulator or breadboard it and find out if it's suitable for the circuit needs. Have you seen the version using a complementary pair on the timer output? There's also a version that parallels two timers outputs to "double" the voltage.

hmm strange . . no idea about parallel two timer outputs , hv to check . .

- - - Updated - - -

A cell phone has a charger circuit in it that has a 5VDC USB input and charges the "3.7V" lithium battery cell to 4.20V. A voltage doubler is not used.
A 555 was used as a voltage doubler about 30 or 40 years ago. The voltage was not doubled, instead it was increased only a little.
A voltage boost converter circuit using a Mosfet and an inductor is used today, but not as a battery charger, it can be used to boost the 3.7V from a lithium battery cell in a power bank to the 5VDC USB used to feed the charger circuit in a cell phone.

hm yeah you told me about that i got that but actually i was about to double voltage from 3.7v battery then with help of 5v zener ckt i was about to plan a handy power bank to connect cell directly as we do normally

 

[BradtheRad]

The complementary pair (post #2) can be in the form of a half-bridge, to drive your charge pump voltage doubler.