dear Mr. Swagatem, how are you?
I'm winantiyo from Indonesia, i've read your post in your blog
and i'm very like it.
i have 2 project:
1. auto roll up power window for car
2. auto lock trigger by foot brake for car
can u help me for the circuit n schematic?
auto up power window: i want my car window can roll up or roll down automatically with single click on power windows button switch
..i ever see the auto roll up module with one relay 8pin, 2 transistor n 4 electrolytic capasitors but it has been broken, 1 resistor n 2 diode. but the series of part has been lost.
there are 5 cables: +12V, ground, 1 cable to motor window, 1 cable to switch power window, and 1 cable again to another motor windows cable..here is the pic:
AUTO LOCK BY FOOT BRAKE: i want to make my car door can locked automatically when all the door closed, key turn ON and i press my foot brake (+trigger). then the door can automatically unlocked when i turn off the key. i hope u understand my explanation...i'm sorry for my english..thank you very much.
Window Glass Up/Down Controller using a Single switch
The shown car power window controller circuit basically consists of three stages: a transistor latch which includes a current sensor, a NAND gate based flip flop stage and a relay driver stage for flipping the motor actions alternately.
The indicated lock/unlock switch toggles the flip flop stage made by engaging three NAND gates from the IC 4093, whose output responds with a permanent high and low alternately with every push of the switch.
R1, R3, R6, R7 = 100K
R5,R8 = 2M2
R9 = 4K7
C1,C4 = 22uF/25V
C2,C3 = 0.22uF
T1,T3 = BC547
RL1,RL2 = 12V/20AMP
ALL DIODES = 1N4007
R10 = TO BE CALCULATED
N1---N3 = IC 4093
This switch also makes sure that the latch section comprising T1 and T2 gets activated in order to allow the supply voltage to reach the remaining part of the circuit.
The output from the flip flop acquired at N2 pin4 is fed to a relay driver stage for activating the power window motor with a forward or a reverse motion depending upon the position of the window glass.
It must be ensured that while connecting the motor the polarity of the wires are set such that a high at pin4 of N2 actuates the window in the closing mode, and vice versa.
The relay is a heavy duty DPDT relay whose N/C, N/O contact connections with the motor enable the motor to carry out the desired to and fro movement.
Normally, reed switches are employed for detecting the completion of the glass up and down movements in order to avoid the motor from getting loaded and destroyed, however here we have a taken a different and a much advanced approach.
In the proposed car power window controller circuit we have employed a current sensor stage in the form of T3, which detects a mounting current across R10 and switches ON itself when the level crosses a set threshold. When T3 switches ON it breaks the T1/T2 latch disconnecting the supply to the motor.
However if a reed switch is incorporated for the above actions, the reed contacts positioned for detecting the up and the down thresholds of the glass may be wired across C1, and T3 stage may be removed entirely. R10 may be replaced with a wire link (see figure below).
Using two switches
The above design could be much simplified if two separate push buttons are employed for the up/down operations of the window glass. The simplified power window circuit which incorporates just a few number of BJTs can be witnessed below.
Four of the above circuits will need to be installed on each door of the vehicle for the required power window switching.
In the next article we'll discuss the brake switch controller stage for the above explained design.