Showing posts with label control. Show all posts
Showing posts with label control. Show all posts
Sunday, May 5, 2013
Brightness Control for small Lamps
This device was designed on request, to control the light intensity of four filament lamps (i.e. a ring illuminator) for close-up pictures with a digital camera, powered by two AA or AAA batteries. Obviously it can be used in other ways, at anyones will.
IC1 generates a 150Hz squarewave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow. Lamp LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the lamp reaches its full brightness.
LP1 could be one or more 1.5V bulbs wired in parallel. Maximum total output current allowed is about 1A.
R2 limits the output voltage, measured across LP1 leads, to 1.5V. Its actual value is dependent on the total current drawn by the bulb(s) and should be set at full load in order to obtain about 1.5V across the bulb(s) leads when P1 is rotated fully clockwise.
Parts:
P1 470K Linear Potentiometer
R1 10K 1/4W Resistor
R2 47K 1/4W Resistor (See Notes)
R3 1K5 1/4W Resistor
C1 22nF 63V Polyester Capacitor
C2 100µF 25V Electrolytic Capacitor
D1,D2 1N4148 75V 150mA Diodes
IC1 7555 or TS555CN CMos Timer IC
Q1 BD681 100V 4A NPN Darlington Transistor
LP1 1.5V 200mA Bulb (See Notes)
SW1 SPST Switch
B1 3V (Two 1.5V AA or AAA cells in series, etc.)
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IC1 generates a 150Hz squarewave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow. Lamp LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the lamp reaches its full brightness.
LP1 could be one or more 1.5V bulbs wired in parallel. Maximum total output current allowed is about 1A.
R2 limits the output voltage, measured across LP1 leads, to 1.5V. Its actual value is dependent on the total current drawn by the bulb(s) and should be set at full load in order to obtain about 1.5V across the bulb(s) leads when P1 is rotated fully clockwise.
Parts:
P1 470K Linear Potentiometer
R1 10K 1/4W Resistor
R2 47K 1/4W Resistor (See Notes)
R3 1K5 1/4W Resistor
C1 22nF 63V Polyester Capacitor
C2 100µF 25V Electrolytic Capacitor
D1,D2 1N4148 75V 150mA Diodes
IC1 7555 or TS555CN CMos Timer IC
Q1 BD681 100V 4A NPN Darlington Transistor
LP1 1.5V 200mA Bulb (See Notes)
SW1 SPST Switch
B1 3V (Two 1.5V AA or AAA cells in series, etc.)
Tuesday, April 9, 2013
Remote Control Circuit Using KT3170
This circuit is which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls. The circuit described here can be used to switch up to nine appliances (corresponding to the digits 1 through 9 of the telephone key-pad). The DTMF signals on telephone instrument are used as control signals. The digit ‘0’ in DTMF mode is used to toggle between the appliance mode and normal telephone operation mode. Thus the telephone can be used to switch on or switch off the appliances also while being used for normal conversation. The circuit uses IC KT3170 (DTMF-to-BCD converter), 74154 (4-to-16-line demulti-plexer), and five CD4013 (D flip-flop) ICs.
The working of the circuit is as follows. Once a call is established (after hearing ring-back tone), dial ‘0’ in DTMF mode. IC1 decodes this as ‘1010,’ which is further demulti-plexed by IC2 as output O10 (at pin 11) of IC2 (74154). The active low output of IC2, after inversion by an inverter gate of IC3 (CD4049), becomes logic 1. This is used to toggle flip-flop-1 (F/F-1) and relay RL1 is energized. Relay RL1 has two changeover contacts, RL1(a) and RL1(b). The energized RL1(a) contacts provide a 220-ohm loop across the telephone line while RL1(b) contacts inject a 10kHz tone on the line, which indicates to the caller that appliance mode has been selected. The 220-ohm loop on telephone line disconnects the ringer from the telephone line in the exchange. The line is now connected for appliance mode of operation. If digit ‘0’ is not dialed (in DTMF) after establishing the call, the ring continues and the telephone can be used for normal conversation. After selection of the appliance mode of operation, if digit ‘1’ is dialed, it is decoded by IC1 and its output is ‘0001’. This BCD code is then demulti-plexed by 4-to-16-line demulti-plexer IC2 whose corresponding output, after inversion by a CD4049 inverter gate, goes to logic 1 state. This pulse toggles the corresponding flip-flop to alternate state. The flip-flop output is used to drive a relay (RL2) which can switch on or switch off the appliance connected through its contacts. By dialing other digits in a similar way, other appliances can also be switched ‘on’ or ‘off’.
Once the switching operation is over, the 220-ohm loop resistance and 10kHz tone needs to be removed from the telephone line. To achieve this, digit ‘0’ (in DTMF mode) is dialed again to toggle flip-flop-1 to de-energize relay RL1, which terminates the loop on line and the 10kHz tone is also disconnected. The telephone line is thus again set free to receive normal calls. This circuit is to be connected in parallel to the telephone instrument
The working of the circuit is as follows. Once a call is established (after hearing ring-back tone), dial ‘0’ in DTMF mode. IC1 decodes this as ‘1010,’ which is further demulti-plexed by IC2 as output O10 (at pin 11) of IC2 (74154). The active low output of IC2, after inversion by an inverter gate of IC3 (CD4049), becomes logic 1. This is used to toggle flip-flop-1 (F/F-1) and relay RL1 is energized. Relay RL1 has two changeover contacts, RL1(a) and RL1(b). The energized RL1(a) contacts provide a 220-ohm loop across the telephone line while RL1(b) contacts inject a 10kHz tone on the line, which indicates to the caller that appliance mode has been selected. The 220-ohm loop on telephone line disconnects the ringer from the telephone line in the exchange. The line is now connected for appliance mode of operation. If digit ‘0’ is not dialed (in DTMF) after establishing the call, the ring continues and the telephone can be used for normal conversation. After selection of the appliance mode of operation, if digit ‘1’ is dialed, it is decoded by IC1 and its output is ‘0001’. This BCD code is then demulti-plexed by 4-to-16-line demulti-plexer IC2 whose corresponding output, after inversion by a CD4049 inverter gate, goes to logic 1 state. This pulse toggles the corresponding flip-flop to alternate state. The flip-flop output is used to drive a relay (RL2) which can switch on or switch off the appliance connected through its contacts. By dialing other digits in a similar way, other appliances can also be switched ‘on’ or ‘off’.
Once the switching operation is over, the 220-ohm loop resistance and 10kHz tone needs to be removed from the telephone line. To achieve this, digit ‘0’ (in DTMF mode) is dialed again to toggle flip-flop-1 to de-energize relay RL1, which terminates the loop on line and the 10kHz tone is also disconnected. The telephone line is thus again set free to receive normal calls. This circuit is to be connected in parallel to the telephone instrument
Digital tone control with MAX5406
The series will I make here is a series regulator of Volume, Bass, and Balance Trable Digital (Tone Control). The core of this circuit is an IC-type output from the Manufacturer Maxim MAX5406, while the IC is an audio processor that comes with the interface switch hit for Tone Control setting above. The circuit scheme is as follows:
The scheme above uses very little supporting components and this makes can be made with a mini size of a matchbox only even if using all SMD components can be reduced in size by half for this time I will only give a simple layout made, following picture:
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| layout components |
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