How to freeform the H-bridge - by Brian Hendrickson

Overview: \ Estimated price per h-bridge:
About $.52 cents to $1.82 dollars depending on where you buy the transistors and in what quantities. I'd recommend Jameco.

Description:
Most of us are familiar with Beckingham's photovore block (also known as Chiu's). The following is a similar format used for freeforming a simple H-bridge motor driver that can be used for walkers, heads, and any other project that uses motors that require a lot of power (100+ ma). Each H-bridge can handle only one motor, but they are so simple, small, and inexpensive you can build as many as needed.
Connections made in each step are highlighted in yellow for clarity.

Parts needed:
2 - 50K or more resistors
4 - 2N3904 Transistors
2 - 2N3906 Transistors

Tools needed:
Soldering iron Solder Wire clippers

Note: there is an error in this tutorial. Make sure you read all the notes.

	1. Here is the legend for the following diagrams. Error: 2N3094 = 2N3904 2N3096 = 2N3906 Sorry about that.
	2. Note: I recommend you look over the entire tutorial before beginning. Start by gluing the transistors together in a block as shown. The 2N3906 transistors (blue) face flat side to the right while the 2N3904 transistors (red) face flat side to the left.
	3. READ NOTE Fold over and solder the pins as shown. The top connection is the (+) power input and the lower connection is the (-) input. Note: See where you bend down the leads on the middle set of 3904's. Don't! Refer to image 5 or 8 to see which lead your really suppost to bend down. Everything else is the same respective to the change.
	4. Connect the two pairs of folded over pins as shown. Note: This step is messes up also. See note on step 3 and refer to step 5 for what it should look like.
	5. Take the base pin (the middle one) of a bottom '04 and connect it with the emitter (lowest pin) of the '04 above and across from it. Do the same for the other lower '04. Look at the figure on the left for clarity.
	6. Then attach the middle (base) pin of one of the '06 to the upper (collector) pin of the '04 below it. Do the same for the other '06.
	7. Finally, attach the two resistors. One connects to the base (middle) pin of an upper '04 and the other resistor attaches to the base pin of the other upper '04. Confused? Look at the drawing to the left.
	8. This is what you should now have.
	9. All you need to do is make the connections to the outside circuitry. 1 = (+) Power in 2 = Motor out 3 = Signal in (from "brain") 4 = (-) Power in 5 = Signal in (from "brain") 6 = Motor out Questions about this tutorial.... hannah@nanospace.com Thanks Brian for this excelent tutorial!!