The BEAM Circuits Collection is a
Mark Tilden's 6-transistor
This is the six transistor "Tilden style" H-bridge; while
not as old as the original "basic
H-bridge," this goes "way back," and is the basis for
many BEAM driver circuits
- Up to 800 mA capacity (using PN2222 and PN2907
- 30 connections per bridge (so, 30 holes if you make a
- Not "smoke-proof" (i.e., it can't handle drive
voltage in both directions at once)
You can read the original Tilden article (complete with
ASCII art) here.
This circuit comes in two flavors -- one triggers on
positive input (non-inverting), the other triggers on
negative input (inverting).
Courtesy of Bruce Robinson, here are diagrams for
free-forming both the inverting and non-inverting flavors of
this circuit (note that these are drawn "dead bug" style,
i.e., with leads "up"):
Bruce Robinson explains:
I did a couple of revised drawings for Ian quite
a while back, so he could put them up at beam-online.
Unfortunately, they didn't get posted in the midst of the
many revisions he was making.
Attached (begging Ian's indulgence), are the two
versions of the circuit, one which turns on with a
Positive input, the other (for quadcores)
with a Negative input.
Ian shows 100k input resistors. I've been using 47k
resistors successfully. Tilden's article recommends
nothing lower than 50k (I assumed 47k was close enough)
and up to 20 Meg or so.
I've also noticed a slight drop in speed when I use
these bridges, but only about 10% or so.
For more information...
Ian Bernstein has a writeup (written by Brian
Hendrickson) on how to free-form an H-bridge motor
(uses an earlier version of the above circuit).
Sebastiaan van V has his own H-bridge free-form
Math Vos has a page
with a different layout for this circuit.