Tuesday, May 14, 2013
TV remote jammer
Here is the circuit diagram of simple but highly effective TV remote jammer circuit. Most of the TV remotes have 38KHz operating frequency. A flood of IR beams in the same frequency can easily confuse the TV receiver and this is the operating principle of our jammer. The circuit is nothing but an astable multivibrator based on NE555 IC. The output of NE555 is amplified using a PNP transistor SK100 to drive the IR LEDs. Not only TV remotes, but any IR remotes operating in the 38KHz frequency region can be also jammed by using this circuit.
Voice modulator circuit
This is a fantyastic circuit for you because you can make various voices through this circuit you can make 7 voices.so try on this and have a fun
Push button switch S1 can be used to activate Vibrato mode and push button switch S4 can be used to activate the Robot mode.S2 and S3 can be used for the upward and downward frequency stepping .
Note
# S5 can be a miniature ON/OFF switch.
# Switches S1 to S4 can be miniature push button switches.
# Do not give more than 4.5v to the circuit.
More...
Push button switch S1 can be used to activate Vibrato mode and push button switch S4 can be used to activate the Robot mode.S2 and S3 can be used for the upward and downward frequency stepping .
Note
# S5 can be a miniature ON/OFF switch.
# Switches S1 to S4 can be miniature push button switches.
# Do not give more than 4.5v to the circuit.
Monday, May 13, 2013
Speach Amplifier
This circuit is intended to be placed in the same box containing the loudspeaker, forming a compact microphone amplifier primarily intended for speech reinforcement. A device of this kind is particularly suited to teachers, lecturers, tourists guides, hostesses and anyone speaking in crowded, noisy environment. The circuits heart is formed by the TDA7052 Audio power amplifier IC, delivering a maximum output of 1.2W @ 6V supply. An external microphone must be plugged into J1, its signal being amplified by Q1 and fed to IC1. R1 acts as a volume control and C3 tailors the upper audio frequency band, mainly to reduce the microphone possibility of picking-up the loudspeaker output, causing a very undesirable and loud "howl", i.e. the well known Larsen effect. Therefore, C3 value can be varied in the 4n7 - 22nF range to ensure the best compromise from speech tone quality and minimum Larsen effect occurrence. Dynamic or electrets microphone is warmly recommended. It has a useful feature that can be used to momentarily mute the microphone by connecting SW1 shown in diagram.
Parts:
P1 = 22K
R1 = 1M
R2 = 15K
R3 = 470R
R4 = 47K
R5 = 4.7K
R6 = 4.7K
C1 = 100nF-63V
C2 = 100nF-63V
C3 = 10nF-63V
C4 = 100nF-63V
C5 = 220uF-25V
C6 = 10uF-25V
Q1 = BC547
IC1 = TDA7052 B1
J1 = Mono Jack Socket
B1 = 6V Battery
SW1 = SPST Slider Switch
SW2 = SPST Toggle Switch
Notes:
* Please note that hands-free, uni-directional headset or ear clip microphone types are very well suited for this device, as also are Clip-on Lavaliere or Lapel microphones.
* If a small electrets capsule is used for the microphone, R5, R6 and C6 must be added to the circuit to provide power supply.
* Choose a loudspeaker as large as possible, in order to increase circuit performance.
* You can use also two 4 Ohm loudspeakers wired in series or two 8 Ohm types wired in parallel in order to obtain better results.
* The box containing the amplifier and loudspeaker(s) can be fitted out with a belt and carried like a shoulder-bag or, if you build a smaller unit, it can be used as a Pick & Go Belt Clip Speaker.
Fridge door Alarm
This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 presents a high resistance (>200K) thus clamping IC1 by holding pin 12 high. When a beam of light enters from the opening, or the fridge lamp illuminates, the photo resistor lowers its resistance (<2k),>220V AC Lamp Toggle Switch Circuit
Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 12Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1A, IC1B, R2, R3 and C3 form a reliable bounce-free toggle switch operated by P1. R4 and C4, wired to pin #6 of IC1B reset the circuit (lamp off) when power supply is applied. IC1C and IC1D wired in parallel act as a buffer, driving the Gate of the Triac through R5. Parts:
R1 = 470R
R2 = 10K
R3 = 100K
R4 = 100K
R5 = 1K
C1 = 330nF-400V
C2 = 100uF-25V
C3 = 100nF-63V
C4 = 10uF-25V
D1 = 1N4007
D2 = 1N4007
D3 = BZX79C12
D4 = TIC206M
IC1 = 4011 NAND Gate
Notes:
* The circuit can be wired permanently to the mains supply as current drain is negligible.
* Due to transformerless design there is no heat generation.
* Low Gate-current Triacs are recommended.
* Obviously, other appliances can be powered in place of a lamp, provided their power dissipation does not exceed about 400W @ 230V
* 110-120Vac operation is easily obtained by simply changing C1 value to 680nF 250V. No further changes are necessary.
* In some cases, e.g. when the controlled device is far from the toggle switch, a pilot LED could be necessary for monitoring purposes. If so, disconnect pin #10 of IC1C from pin #11 of IC1D and wire a LED and its 1K series current limiting resistor across pin #10 of IC1C and negative supply.
* Warning! The circuit is connected to 230Vac mains, so some parts in the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged in and enclose it in a plastic box.
* P1 will SPST Pushbutton
Sunday, May 5, 2013
The Link Telephone Intercom
The “Link” intercom has been designed in such a way that you can buy parts for it ‘off the shelf’ at just about any decent electronics retail chain. It uses old pulse dial handsets and replaces the AC bell set with a 9 volt DC buzzer. The whole circuit runs from a 12 volt regulated DC supply and is suitable for short term battery operation (eg: ‘Gel Cell’). It is suitable for radio field days and sporting events (providing you can scrounge enough 4 wire cable) and may find a place in pre-schools, old folk’s homes, boy scout/girl guide halls, churches, kids’ tree houses/fortresses, or maybe even more serious uses such as small offices, factories, workshops and many other applications.
The Link telephone intercom is designed around two ICs. The first, IC1, is an NE 556 dual timer chip, which is wired up to provide dial tone, ring tone (busy tone too, which will be explained along with a few add-ons to be mentioned later on) and ring pulses for the ringer circuit attached to each line circuit. The other chip, IC 2, is a CD 4017B decade counter, which is wired to count each train of dial pulses as they are received and buffered by the two opto-couplers, OC1 and OC 2 and their associated R/C networks.
Line Circuits
Each phone handset is connected by a four wire circuit from the ‘black box’. Two wires (normally tagged ‘white’ and ‘blue’ here in Oz) are for speech and dialing functions, whereas the other two (tagged locally as ‘red’ and ‘black’) are for the ring pulses supplied by the ringer circuit to each DC buzzer inside the handsets. When a phone (eg: #1 for our discussion) is picked up in its ‘off hook’ condition, a DC loop is formed by the following components: DC circuitry inside the phone, the 1K winding of transformer TX, and back to 0V- earth. Taken from the +12 volts terminal, through the Leds inside OC1 and OC2 and back to the phone handset.
Making A Call
Dial tone is provided to the calling party’s phone when the Link is in its ‘reset’ condition (no calls in progress) via capacitor C3 and the 8 ohm winding (8R) of TX to 0v- earth. This and the other service tones are generated by IC1a, while ring pulses are generated by IC1b. When a calling party’s phone is ‘off hook’, the leds force the photo transistors to switch on hard, pulling pins 13 and 14 of IC2 to 0 volts ground. When the dial inside the phone handset is pulled back and released, the collector lead of OC2’s transistor is held low at 0 volts by the slow release charging of C5. Pin 13 of IC2 is a CE (chip enable) input, and needs to stay at a logic low (near 0 volts) to enable pin 14 to count the dial pulses. So while ‘impulsing’ occurs, pin 13 stays low, and pin 14 alternates between logic high and low as the led emulates each dial pulse train, until the last pulse in the train is received.
Dialing Into The Register
When caller number #1 dials phone number # 4, those four pulses appear across the leds inside OC1 and OC2. The decade counter, acting as a Register (a storage device used in communications equipment for storing dialed digits) counts these pulses, turning its output pins on and off inn unison, with the last dial pulse causing the counter to rest on the last output pin that is turned on. The complete sequence for a maximum of ten pulses in the one pulse train, is (pin 3 is always at logic high at ‘reset’) 2,4,7,10, and then 1,5,6,9,11 and then finally pin 3. So when the number ‘4’ is dialed, the counter would step through pins 2,4,7, and then land on pin 10, which is connected to phone #4’s ringer circuit via Q4’s base lead.
The Ringer Circuit
Each line circuit consists of the individual phone handset, the DC buzzer mounted inside it, the common connections to TX and the cathode of OC2’s led, as well as transistors Q1 to Q4 and common driver transistor Q5. With pin 3 of IC2 at logic high on ‘reset’, diode D3 enables IC2a to provide a Dial Tone from pin 5. When a number is dialed, pin 3 of IC2 goes low on the first dial pulse, removing the logic high via D4 from pins 12 and 8 of IC1b, thus enabling it to charge up C3, and produce ring pulses to IC1a via diode D5, (from pin 9 to pin 4). After about 2 seconds, ring pulses commence, and the modulated dial tone (which then by default becomes an interrupted Ring Tone to the caller) is produced at pin 5 of IC1a, indicating the progress of the call.
True Ring Trip
When the called party answers the call, transistor QX with trimpot R6, (adjusted to detect both phones being ‘off-hook’,) triggers the led and phototransistor inside OC3. This halts the ring pulses and ring tone supplied by IC1a and IC1b for the duration of that call, by supplying a logic high potential to pins 12 and 8 of IC1b via D6. When the call is over, and both parties have hung up their phone handsets (eg: back to the ‘on-hook’ status,) the DC loop formed by the handsets, TX and OC1/OC2 is broken. Pin 13 of IC2 returns to its reset potential of logic high, and extends this high to pin 15 (Reset) of the 4017 decade counter chip, which disables the output selected during the dialing operation, and enables pin 3 to high, thus restoring Dial Tone to the next caller via pin 4 of IC1a.
Resetting The Link
Thus the Link is fully reset and ready for another call. As you can see, it may seem a little complicated to follow the progression through a call, particularly if you haven’t been involved with phones and logic chips much before. At the end of the day, you have some simple counting, pulsing and interfacing circuitry, which will perform all the necessary tasks of a basic intercom, and all at a reasonable cost. I used some formatted matrix board for the p.c.b and IC sockets for all ICs and OC/OC2. I also found that a heat sink fin for the 7812 regulator chip was unnecessary. A box could be used for housing the Link circuitry, and some kind of screw terminal block or ID block (like a small 10 pair KRONE junction box) could be used to terminate the wiring at the box to make it look more professional. Remember these two things. If you leave a phone ‘off-hook’ you will lock up the Link and if you pick up a phone when someone else is dialing, wrong numbers will result. Apart from that, have fun! Austin Hellier 08-Oct-2003
Parts
R1 10k
R2 150k
R3 4k7
R4 47k
R5 2k2
R6 4k7 trimpot
R7 390R
R8 10k
R9 100k
R10 100k
R11 22k
R12-R15 2k2
R16 4k7
R17 4k7
C1 0.22uF
C2 47uF
C3 1uF
C4 2,200uF (power filter cap – not shown, but wired across +12volts & 0v- ground points
Q1-Q5 BC547 n.p.n low gain
Q6 BC 549C high gain with a beta of at least 250+
D1-D7 1N4148 or 1N914 small signal diodes
IC1 NE 556 dual timer chip
IC2 CD 4017B decade counter chip
OC1-OC3 4N25 or 4N28 opto couplers
Tx 1k/8R transformer, with 1k centre tapped
B1-B4 9 volt DC buzzers mounted inside phone handsets
Miscellaneous – wire, cable, matrix or prototyping board, solder, case, 15 volt DC 200ma plug pack
power supply, phone sockets, zip ties, 7812 regulator and filter caps etc.
More...
The Link telephone intercom is designed around two ICs. The first, IC1, is an NE 556 dual timer chip, which is wired up to provide dial tone, ring tone (busy tone too, which will be explained along with a few add-ons to be mentioned later on) and ring pulses for the ringer circuit attached to each line circuit. The other chip, IC 2, is a CD 4017B decade counter, which is wired to count each train of dial pulses as they are received and buffered by the two opto-couplers, OC1 and OC 2 and their associated R/C networks.
Line Circuits
Each phone handset is connected by a four wire circuit from the ‘black box’. Two wires (normally tagged ‘white’ and ‘blue’ here in Oz) are for speech and dialing functions, whereas the other two (tagged locally as ‘red’ and ‘black’) are for the ring pulses supplied by the ringer circuit to each DC buzzer inside the handsets. When a phone (eg: #1 for our discussion) is picked up in its ‘off hook’ condition, a DC loop is formed by the following components: DC circuitry inside the phone, the 1K winding of transformer TX, and back to 0V- earth. Taken from the +12 volts terminal, through the Leds inside OC1 and OC2 and back to the phone handset.
Making A Call
Dial tone is provided to the calling party’s phone when the Link is in its ‘reset’ condition (no calls in progress) via capacitor C3 and the 8 ohm winding (8R) of TX to 0v- earth. This and the other service tones are generated by IC1a, while ring pulses are generated by IC1b. When a calling party’s phone is ‘off hook’, the leds force the photo transistors to switch on hard, pulling pins 13 and 14 of IC2 to 0 volts ground. When the dial inside the phone handset is pulled back and released, the collector lead of OC2’s transistor is held low at 0 volts by the slow release charging of C5. Pin 13 of IC2 is a CE (chip enable) input, and needs to stay at a logic low (near 0 volts) to enable pin 14 to count the dial pulses. So while ‘impulsing’ occurs, pin 13 stays low, and pin 14 alternates between logic high and low as the led emulates each dial pulse train, until the last pulse in the train is received.
Dialing Into The Register
When caller number #1 dials phone number # 4, those four pulses appear across the leds inside OC1 and OC2. The decade counter, acting as a Register (a storage device used in communications equipment for storing dialed digits) counts these pulses, turning its output pins on and off inn unison, with the last dial pulse causing the counter to rest on the last output pin that is turned on. The complete sequence for a maximum of ten pulses in the one pulse train, is (pin 3 is always at logic high at ‘reset’) 2,4,7,10, and then 1,5,6,9,11 and then finally pin 3. So when the number ‘4’ is dialed, the counter would step through pins 2,4,7, and then land on pin 10, which is connected to phone #4’s ringer circuit via Q4’s base lead.
The Ringer Circuit
Each line circuit consists of the individual phone handset, the DC buzzer mounted inside it, the common connections to TX and the cathode of OC2’s led, as well as transistors Q1 to Q4 and common driver transistor Q5. With pin 3 of IC2 at logic high on ‘reset’, diode D3 enables IC2a to provide a Dial Tone from pin 5. When a number is dialed, pin 3 of IC2 goes low on the first dial pulse, removing the logic high via D4 from pins 12 and 8 of IC1b, thus enabling it to charge up C3, and produce ring pulses to IC1a via diode D5, (from pin 9 to pin 4). After about 2 seconds, ring pulses commence, and the modulated dial tone (which then by default becomes an interrupted Ring Tone to the caller) is produced at pin 5 of IC1a, indicating the progress of the call.
True Ring Trip
When the called party answers the call, transistor QX with trimpot R6, (adjusted to detect both phones being ‘off-hook’,) triggers the led and phototransistor inside OC3. This halts the ring pulses and ring tone supplied by IC1a and IC1b for the duration of that call, by supplying a logic high potential to pins 12 and 8 of IC1b via D6. When the call is over, and both parties have hung up their phone handsets (eg: back to the ‘on-hook’ status,) the DC loop formed by the handsets, TX and OC1/OC2 is broken. Pin 13 of IC2 returns to its reset potential of logic high, and extends this high to pin 15 (Reset) of the 4017 decade counter chip, which disables the output selected during the dialing operation, and enables pin 3 to high, thus restoring Dial Tone to the next caller via pin 4 of IC1a.
Resetting The Link
Thus the Link is fully reset and ready for another call. As you can see, it may seem a little complicated to follow the progression through a call, particularly if you haven’t been involved with phones and logic chips much before. At the end of the day, you have some simple counting, pulsing and interfacing circuitry, which will perform all the necessary tasks of a basic intercom, and all at a reasonable cost. I used some formatted matrix board for the p.c.b and IC sockets for all ICs and OC/OC2. I also found that a heat sink fin for the 7812 regulator chip was unnecessary. A box could be used for housing the Link circuitry, and some kind of screw terminal block or ID block (like a small 10 pair KRONE junction box) could be used to terminate the wiring at the box to make it look more professional. Remember these two things. If you leave a phone ‘off-hook’ you will lock up the Link and if you pick up a phone when someone else is dialing, wrong numbers will result. Apart from that, have fun! Austin Hellier 08-Oct-2003
Parts
R1 10k
R2 150k
R3 4k7
R4 47k
R5 2k2
R6 4k7 trimpot
R7 390R
R8 10k
R9 100k
R10 100k
R11 22k
R12-R15 2k2
R16 4k7
R17 4k7
C1 0.22uF
C2 47uF
C3 1uF
C4 2,200uF (power filter cap – not shown, but wired across +12volts & 0v- ground points
Q1-Q5 BC547 n.p.n low gain
Q6 BC 549C high gain with a beta of at least 250+
D1-D7 1N4148 or 1N914 small signal diodes
IC1 NE 556 dual timer chip
IC2 CD 4017B decade counter chip
OC1-OC3 4N25 or 4N28 opto couplers
Tx 1k/8R transformer, with 1k centre tapped
B1-B4 9 volt DC buzzers mounted inside phone handsets
Miscellaneous – wire, cable, matrix or prototyping board, solder, case, 15 volt DC 200ma plug pack
power supply, phone sockets, zip ties, 7812 regulator and filter caps etc.
Wednesday, May 1, 2013
Short Wave Converter
This short-wave converter, which doesn’t have a single coil requiring alignment, is intended to enable simple medium-wave receivers to be used to listen to short-wave signals. The converter transforms the 49-m short-wave band to the medium-wave frequency of 1.6 MHz. At the upper end of the medium-wave band, select an unoccupied frequency that you want to use for listening to the converted short-wave signals. Good reception performance can be obtained using a wire antenna with a length of one to two metres.The converter contains a free-running oscillator with a frequency of around 4.4 MHz, which is tuned using two LEDs (which act as variable-capacitance diodes!) and a normal potentiometer. The frequency range is set by adjusting the emitter current using a 1k trimpot. The oscillator frequency depends strongly on the operating point. This is due to the combination of using an audio transistor and the extremely low supply voltage. Under these conditions, the transistor capacitances are relatively large and strongly dependent on the operating point. The second transistor forms the mixer stage.
If you calculate the resonant frequencies of the tuned circuits, you will obtain 6.7 MHz for the antenna circuit and 1.7 MHz for the output circuit. Additional transistor capacitance and the effects of the coupling capacitors shift each of the resonant frequencies downward. The tuned circuits are relatively heavily damped to obtain bandwidths that are large enough to allow the circuit to be used without any specific alignment. The results are good despite the low collector–emitter voltage of around only 0.6 V, due to the fact that only a modest amount of mixer gain is necessary. The entire circuit also draws less than 1mA.
If you calculate the resonant frequencies of the tuned circuits, you will obtain 6.7 MHz for the antenna circuit and 1.7 MHz for the output circuit. Additional transistor capacitance and the effects of the coupling capacitors shift each of the resonant frequencies downward. The tuned circuits are relatively heavily damped to obtain bandwidths that are large enough to allow the circuit to be used without any specific alignment. The results are good despite the low collector–emitter voltage of around only 0.6 V, due to the fact that only a modest amount of mixer gain is necessary. The entire circuit also draws less than 1mA.
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