AC Motor Speed Controller

Part-Total Qty.
R1 -1- 27K 1W Resistor
R2 -1 -10K 1/4W Resistor
R3 -1- 100K 1/4W Resistor
R4 -1 -33K 1/4W Resistor
R5 -1- 2.2K 1/4W Resistor
R6 -1- 1K 1/4W Resistor
R7 -1- 60K Ohm 1/4W Resistor
R8 -1- 3K Linear Taper Trim Pot
R9 -1- 5K Linear Taper Pot
R10 -1- 4.7K Linear Taper Trim Pot
R11 -1- 3.3K 1/4W Resistor
R12 -1- 100 Ohm 1/4W Resistor
R13 -1- 47 Ohm 1W Resistor (See Notes)
C1, C3 -2- 0.1uF Ceramic Disc Capacitor
C2 -1- 100uF 50V Electrolytic Capacitor
D1 -1- 6V Zener Diode
Q1 -1- 2N2222 NPN Transistor 2N3904
SCR1 -1- ECG5400
TR1 -1- TRIAC (See Notes)
U1 -1- DIAC Opto-Isolator (See Notes)
BR1, BR2 -2- 5A 50V Bridge Rectifier
T1 -1- Transformer (See Notes)
MISC -1- PC Board, Case, Line Cord, Socket For U1, Heatsinks

Notes

TR1 must be chosen to match the requirements of the load. Most generic TRIACs with ratings to support your load will work fine in this circuit. If you find a TRIAC that works well, feel free to leave a comment.

U1 must be chosen to match the ratings of TR1. Most generic DIAC based opto-isolators will work fine. If you have success with a specific part, feel free to leave a comment.

T1 is any small transformer with a 1:10 turns ratio. The circuit is designed to run on 120V so a 120V to 12V transformer will work. Alternately, you can wind T1 on a transformer core using a primary of 25 turns, a secondary of 200 turns, and 26 gauge magnet wire.

R9 is used to adjust motor speed. R10 is a trim pot used to fine tune the governing action of the circuit. R8 fine tunes the feedback circuit to adjust for proper voltage at the gate of SCR1. It should be adjusted to just past the minimum point at which the circuit begins to operate.

R13 must be chosen to match the load. Generally, larger loads will require a smaller value.

Since this circuit is not isolated from mains, it must be built in an insulated case.

Source - Aaroncake.net

DC Motor Reversing Circuit

Description:
A DC motor reversing circuit using non latching push button switches. Relays control forward, stop and reverse action, and the motor cannot be switched from forward to reverse unless the stop switch is pressed first.
Notes:
Except for the back emf diodes across the relay coils this circuit is identical in function to the example shown on the relay contact labeling guide in the practical section. At first glance this may look over-complicated, but this is simply because three non-latching push button switches are used. When the forward button is pressed and released the motor will run continuously in one direction. The Stop button must be used before pressing the reverse button. The reverse button will cause the motor to run continuously in the opposite direction, or until the stop button is used. Putting a motor straight into reverse would be quite dangerous, because when running a motor develops a back emf voltage which would add to current flow in the opposite direction and probably cause arcing of the relay contacts. This circuit has a built-in safeguard against that condition.

Circuit Operation:
Assume that the motor is not running and that all relays are unenergized. When the forward button is pressed, a positive battery is applied via the NC contacts of B1 to the coil of relay RA/2. This will operate as the return path is via the NC contacts of D1. Relay RA/2 will operate. Contacts A1 maintain power to the relay even though the forward button is released. Contacts A2 apply power to the motor which will now run continuously in one direction. If now the reverse button is pressed, nothing happens because the positive supply for the switch is fed via the NC contact A1, which is now open because Relay RA/2 is energized. To Stop the motor the Stop switch is pressed, Relay D operates and its contact D1 breaks the power to relays A and B, (only Relay A is operated at the moment). If the reverse switch is now pressed and released. Relay B operates via NC contact A1 and NC contact D1. Contact B1 closes and maintains power so that the relay is now latched, even when the reverse switch is opened. Relay RC/2 will also be energized and latched. Contact B2 applies power to the motor but as contacts C1 and C2 have changed position, the motor will now run continuously in the opposite direction. Pressing the forward button has no effect as power to this switch is broken via the now open NC contact B1. If the stop button is now pressed. Relay D energizes, its contact D1 breaks power to relay B, which in turn breaks power to relay C via the NO contact of B1 and of course the motor will stop. All very easy. The capacitor across relay D is there to make sure that relay D will operate at least longer than the time relays A,B and C take to release.

Correction to Diagram
In the original circuit a diode was omitted, this is the diode now in series with relay coils RA and RD. Special thanks to Christian Sanchez from Ecuador for pointing this mistake out. Without the diode relay RA remains energized, its holding current path is through relay coils RB and RC, the diode now breaks the path,

Simple Servo Controller

Parts

Part - TotalQty. - Description
R1 - 1 - 820 Ohm 1/4W Resistor
R2 - 1 - 68K 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 1K Linear Taper Pot
C1 - 1 - 1uF 16V Electrolytic Capacitor
Q1 - 1 - 2N3904 NPN Transistor or 2N2222, Most Small Signal Transistors
U1 - 1 - 555 Timer IC
MISC - 1 - Board, Wire, Knob For R1, 8 Pin Socket For U1

Notes

R1 adjusts the position of the servo.

Connect the servo to the circuit as shown in the schematic. For common Futaba servos, the red wire is power, the black wire is ground, and the white wire is control.

DC Motor Control Circuit

Notes:
Here, S1 and S2 are normally open , push to close, press button switches. The diodes can be red or green and are there only to indicate direction. You may need to alter the TIP31 transistors depending on the motor being used. Remember, running under load draws more current.This circuit was built to operate a small motor used for opening and closing a pair of curtains. As an advantage over automatic closing and opening systems, you have control of how much, or how little light to let into a room.The four diodes surriunding the motor, are back EMF diodes. They are chosen to suit the motor. For a 12V motor drawing 1amp under load, I use 1N4001 diodes.