LEAD ACID BATTERY CHARGER

Parts List:

R1 = 0.56 Ohm, 5W, WW     C1 = 1000uF/63V           Q1 = BC140
R2 = 470 Ohm              C2 = 220nF                Q2 = LM317, Adj. Volt Reg.
R3 = 120 Ohm              C3 = 220nF                      (On large coolrib!)
R4 = 100 Ohm 
P1 = 220 Ohm

Description:

The above pictured schematic diagram is just a standard constant current model with a added current limiter, consisting of Q1, R1, and R4. The moment too much current is flowing biases Q1 and drops the output voltage.

The output voltage is: 1.2 x (P1+R2+R3)/R3 volt. Current limiting kicks in when the current is about 0.6/R1 amp.
For a 6-volt battery which requires fast-charging, the charge voltage is 3 x 2.45 = 7.35 V. (3 cells at 2.45v per cell). So the total value for R2 + P1 is then about 585 ohm. For a 12 V battery the value for R2 + P1 is then about 1290 ohm.

For this powersupply to work efficiently, the input voltage has to be a minimum of 3V higher than the output voltage.

P1 is a standard trimmer potentiometer of sufficient watt for your application.

The LM317 must be cooled on a sufficient (large) coolrib.

Q1 (BC140) can be replaced with a NTE128 or the older ECG128 (same company).

Except as a charger, this circuit can also be used as a regular power supply.

STEPPER MOTOR CONTROL

STEPPER MOTOR CONTROL USING GATES & FLIP FLOP

DSCRIPTION



I found this circuit in my files. I don't know where it came from, but it looks like I photocopied it from somewhere years ago. I have been told that it came from "The Robot Builder's Bonanza", by Gordan McComb. Anyway, I thought that it should be fairly useful, so I decided to post it here. The circuit is very simple and inexpensive. This is good thing because most commercial stepper motor controller ICs are quite expensive. This circuit is built from standard components and can easily be adapted to be controlled by a computer. If you use cheap surplus transistors and stepper motor, the price of the circuit can be kept to under $10.
Schematic




Parts

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R1, R2 ,R3, R4

(4) 1K 1/4W Resistor

D1, D2, D3, D4

(4 )1N4002 Silicon Diode

Q1, Q2, Q3, Q4

( 4) TIP31 NPN Transistor (See Notes) TIP41, 2N3055

U1

(1) 4070 CMOS XOR Integrated Circuit

U2

(1) 4027 CMOS Flip-Flop

S1

(1) SPDT Switch

MISC

(1 )Case, Board, Wire, Stepper Motor

Notes

1. You should be able to substitute any standard (2N3055, etc.) power transistor for Q1-Q4.
2. Every time the STEP line is pulsed, the motor moves one step.
3. S1 changes the motors direction.

STEPPER MOTOR CONTROL USING IC UCN580

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DESCRIPTION

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This is a very good integrated circuit. There is no need for any external glue logic to drive the circuit, there is only 2 pins to drive the motor, one for controlling the direction and the other to trigger the stepping pulses. It provides a very compact design that drives 5 or 6 or 8 wire stepper motors. The 5 or 8 wire stepper motors are treated as a variation on the 6 wire motor. That is, the 5 has the two common wires from the coils center taps joined inside the motor (saves joining them outside the motor), however some confusion may occur with the ends of the other coils as to which joins with which, however trial and error to determine this will not hurt anything. In the 8 wire motor case the joined center taps will have to worked out by you. You will know which coil is joined to which coil, however experimentation may be required to determine polarity