Hi there, I love your circuit, and used many ideas from it to build my own switching reg USB charger out of a National step-up boost converter instead (and Penguin mint tin instead of your weak Altoid bollocks! ^_^). Now, one thing, I'm a compsci and therefore my analogue electronics ability is somewhat lacking (although I'm reasonably familiar with digital circuitry).
As I'm not too familiar with inductors because of this, I was doing some reading up on them and noticed something about a circuit called a gyrator, which can simulate a real inductor with capacitors and an op-amp (or transistors). The article said they're commonly used in place of real inductors with ICs, as inductors are quite massive, especially when you compare to to-day's SMD tech. I thought this might be quite useful, as I had a hell of a time obtaining an inductor for my switcher, and the shipping I paid was equivalent to around ten inductors just by themselves. However, the article also said there are a few limitations, such as you can't get high Q factors, and the circuit has more resistance than a real inductor. It also said they are used mostly for quite high inductor values, such as 1 henry (and the max758 you used asks for a 22mH inductor, no?).
So my question is, is it feasible to use a gyrator circuit to replace the large, bulky, inconvenient inductor in your and other switching reg circuits?
-Tommi
Using a gyrator circuit instead of an inductor
Moderators: adafruit_support_bill, adafruit
Please be positive and constructive with your questions and comments.
-
- Posts: 2
- Joined: Mon Jul 24, 2006 1:25 am
-
- Posts: 2
- Joined: Mon Jul 24, 2006 1:25 am
Heh I guess not.
After googling a little, I found this interesting paper though:
http://users.ece.gatech.edu/~rincon/pub ... d_mult.pdf
It describes using an inductor `multiplier'. It even deals specifically with switchers. It's all very academic in the paper (being a paper and all) but I might play with this and an RF inductor or something this weekend...
On another note, I have built another USB charger with another sort of switching regulator; a charge pump. I chose this because I'm looking for small size, and asking another compsci I know who programmes microcontrollers (so therefore small things which are portable ^_^) he let me know about these charge pumps which are 8-pin, SMD, and require a couple of capacitors and no inductor. There aren't many that supply enough current though, but I did find a couple that can do more than ~120mA... my one was from Microchip. Less efficient than a boost converter though.
Isn't electronics fun? Sometimes I think I'm in the wrong field heheh... I like playing with these funny little be-wired black boxes...
After googling a little, I found this interesting paper though:
http://users.ece.gatech.edu/~rincon/pub ... d_mult.pdf
It describes using an inductor `multiplier'. It even deals specifically with switchers. It's all very academic in the paper (being a paper and all) but I might play with this and an RF inductor or something this weekend...
On another note, I have built another USB charger with another sort of switching regulator; a charge pump. I chose this because I'm looking for small size, and asking another compsci I know who programmes microcontrollers (so therefore small things which are portable ^_^) he let me know about these charge pumps which are 8-pin, SMD, and require a couple of capacitors and no inductor. There aren't many that supply enough current though, but I did find a couple that can do more than ~120mA... my one was from Microchip. Less efficient than a boost converter though.
Isn't electronics fun? Sometimes I think I'm in the wrong field heheh... I like playing with these funny little be-wired black boxes...
Please be positive and constructive with your questions and comments.