Stan Swan wrote:
Although I applaud making an H bridge for it's educational benefits,the L293D is THE industry standard approach for modest power motors & just HAS to be considered ! I recall it's arival was akin to the 555 (1972)whereby zillions of discretes were done away with. Crucial hence you feature it at your presentation...
Hi Stan,
As a relative newcomer to the Picaxe scene I highly appreciate the major contributions you have made to this community.
Please consider my comments then as quasi- complimentary with a hint of humor 8^).
To paraphrase Shrek: chip are like onions.
Yes, "consider" using a L293 but I respectfully disagree that it is "crucial to feature it" for many of the reasons you mentioned.
Given this is the Picaxe Forum, so single chip solutions like the L293 would seem a natural extension for reasons of economy and convenience.
But in an educational setting, a presentation using a discrete version of a functional block like a motor driver especially if it is a novel solution, may get you higher marks compared to using a single chip "black box".
Without peeling back the hidden layers, most people will never know just where all that magic smoke comes from.
Using a discrete designs not only reveals useful details, helpful to the learning process, but also let's you tweak performance for a specific application.
The L293 chip has been around for a long time and while it may be widely used by hobbyists now, imho it is not an ideal motor driver and in fact is rarely used in commercial applications such as printers, consumer electronics, toys, etc.
Yes, it is a single chip solution and yes it is robust. But note that the typical output voltage drop is 2.6V at 600mA which makes it very inefficient when used with the minimum motor supply voltage of 4.5V.
If you must use a motor driver chip for a low voltage application consider newer more efficient low saturation voltage CMOS types that are widely used in consumer electronics.
Having said that, thanks again for all your helpful writings on all things Picaxe.
cheers
wilf
NB: The original H-bridges? thread started by jadesteffen specifically requested an h-bridge design using only 2N2222 transistors and 1K resistors to drive toy motors, a solution presumably dictated by limited resources.
So I wrote:
This 6 transistor quasi-complementary full feature h-bridge can be found here.
http://groups.yahoo.com/group/beam/files/wilf_nv/Quasihbridge.gif
Although I applaud making an H bridge for it's educational benefits,the L293D is THE industry standard approach for modest power motors & just HAS to be considered ! I recall it's arival was akin to the 555 (1972)whereby zillions of discretes were done away with. Crucial hence you feature it at your presentation...
Hi Stan,
As a relative newcomer to the Picaxe scene I highly appreciate the major contributions you have made to this community.
Please consider my comments then as quasi- complimentary with a hint of humor 8^).
To paraphrase Shrek: chip are like onions.
Yes, "consider" using a L293 but I respectfully disagree that it is "crucial to feature it" for many of the reasons you mentioned.
Given this is the Picaxe Forum, so single chip solutions like the L293 would seem a natural extension for reasons of economy and convenience.
But in an educational setting, a presentation using a discrete version of a functional block like a motor driver especially if it is a novel solution, may get you higher marks compared to using a single chip "black box".
Without peeling back the hidden layers, most people will never know just where all that magic smoke comes from.
Using a discrete designs not only reveals useful details, helpful to the learning process, but also let's you tweak performance for a specific application.
The L293 chip has been around for a long time and while it may be widely used by hobbyists now, imho it is not an ideal motor driver and in fact is rarely used in commercial applications such as printers, consumer electronics, toys, etc.
Yes, it is a single chip solution and yes it is robust. But note that the typical output voltage drop is 2.6V at 600mA which makes it very inefficient when used with the minimum motor supply voltage of 4.5V.
If you must use a motor driver chip for a low voltage application consider newer more efficient low saturation voltage CMOS types that are widely used in consumer electronics.
Having said that, thanks again for all your helpful writings on all things Picaxe.
cheers
wilf
NB: The original H-bridges? thread started by jadesteffen specifically requested an h-bridge design using only 2N2222 transistors and 1K resistors to drive toy motors, a solution presumably dictated by limited resources.
So I wrote:
This 6 transistor quasi-complementary full feature h-bridge can be found here.
http://groups.yahoo.com/group/beam/files/wilf_nv/Quasihbridge.gif