Not sure how did this circuit generate 24VAC from DC

[shemo]

1)How did IC1 generate 24V from 3.6V DC battery??
2)C1 is voltage filter but what's the purpose of L1, a filter for what?
3)what's the use of D1, schottky diode here?

 

[betwixt]

1. It's a simple boost regulator. In simple terms, pin 7 of the LT1303 is periodically (at several KHz) switched to ground then disconnected again. When grounded, all the 3.7V is connected across L1 which builds a magnetic field in it. When opened, the magnetic field collapses and releases it's energy through the only path available which is through D1. By adjusting the frequency and value of L1 enough energy can be stored and released to make 24V.

2. C1 is there as a local power reservoir for the LT1303. It likes it's own supply to be 'clean' and C1, which should be mounted close to it, minimizes the ripple on the 3.7V caused by L1 current being switched on an off.

3. Schottky diodes are idea for this application because they store very little charge across their junction. An ordinary diode has a relatively long recovery time, meaning they are not suitable in positions where the voltage and current is switched on and off very rapidly. Schottky diodes don't store as much of the charge that causes the slow recovery so they work better at higher frequency.

Brian.

 

[crutschow]

Schottky diodes have a lower forward voltage drop than standard silicon diodes, so are more efficient from that standpoint also.

 

[BradtheRad]

The thread below contains posts about the theory behind switched-coil converters.
My posts have links to my tutorial simulations, including a boost converter.

These are done in Falstad's animated interactive simulator (Java applet).
The links will open the website, load my schematic, and run it on your computer.

https://www.edaboard.com/threads/268178/