Friday, September 19, 2014
Homebrew DCF 77 Signal Generator
The DCF77 signal is a long-wave time signal transmitted from Mainflingen, Germany, providing highly accurate time synchronization across Europe. This signal is used in clocks, timers, and devices requiring precise timekeeping. Building a homebrew DCF77 signal generator allows hobbyists to experiment with time synchronization for clocks or even emulate a DCF77 signal in areas without reception.
This article outlines how to create your own DCF77 signal generator using basic electronic components and microcontroller programming.
Understanding DCF77 Signals
The DCF77 signal carries both time and date information. It is transmitted on a 77.5 kHz carrier wave modulated by amplitude. Each minute, 59 bits of information are transmitted:
- Seconds 0-20: Reserved for status information.
- Seconds 21-58: Encodes time, date, and parity bits.
- Second 59: A blank bit (no signal) indicates the end of a minute.
The signal uses pulse-width modulation:
- A short pulse (100 ms) represents a binary 0.
- A long pulse (200 ms) represents a binary 1.
Components Required
To build a DCF77 signal generator, you will need:
- Microcontroller: Arduino or ESP32 is recommended for flexibility.
- Crystal Oscillator: For generating a stable 77.5 kHz carrier wave.
- Transistors/MOSFETs: For signal amplification.
- Resistors and Capacitors: For signal conditioning.
- Breadboard/PCB: For prototyping the circuit.
- Coil Antenna: To simulate the DCF77 signal wirelessly (optional).
- Power Supply: Suitable for your microcontroller and additional components.
Circuit Design
The DCF77 generator can be broken into three stages:
1. Carrier Wave Generation
Generate a stable 77.5 kHz sine or square wave using the microcontroller. Alternatively, use a crystal oscillator to produce the frequency directly.
2. Amplitude Modulation
Use the microcontroller to modulate the carrier wave based on the DCF77 data bits. This involves toggling between a high and low amplitude to encode the signal.
3. Signal Transmission
Optionally amplify and transmit the signal through a coil antenna to nearby receivers. If using a wired connection, output the modulated signal directly.
Programming the Microcontroller
A microcontroller such as Arduino can handle signal modulation. Below is an example sketch for Arduino:
This program generates a 77.5 kHz carrier wave and modulates it based on DCF77 timing. You can customize the timing to match the official signal encoding.
Testing the Signal
- Use an oscilloscope to verify the carrier frequency and amplitude modulation.
- Place a DCF77-compatible clock nearby to test if it syncs with the signal.
- Experiment with signal strength and antenna placement for optimal results.
Applications
- Clock Calibration: Synchronize clocks in areas without DCF77 reception.
- Educational Tool: Learn about signal generation and timekeeping protocols.
- Custom Time Servers: Integrate with IoT devices needing precise time.
Conclusion
Building a homebrew DCF77 signal generator is an engaging project combining electronics, programming, and physics. With minimal components and basic programming, you can simulate a highly accurate time signal. Whether for educational purposes or practical applications, this project is a rewarding addition to any DIY electronics portfolio.
Tuesday, February 4, 2014
Car 12V to 50V DC Converter Circuit Diagram
Car 12V to 50V DC Converter Circuit Diagram
This circuit for Car audio input battery 12V to 50VDC, It use transistor and IC TL072.
This circuit for Car audio input battery 12V to 50VDC, It use transistor and IC TL072.
Saturday, January 11, 2014
cell phone jammer is to shield the GSM frequency band
cell phone jammer is to shield the GSM frequency
band, CDMA frequency band and 3G frequency band at the same time.
And broadcasting 24 hours. Fourth, the development prospects of Chinas mobile TV and countermeasures of Chinas mobile TV prospects for the development and Countermeasures 4.1 bottlenecks in the
development of mobile TV to the diverse needs of the audience on the mobile terminal is gradually increasing, making the mobile TV market has shown signs of the trend gaining momentum, the future
can not Limited. Country in the process of development of mobile TV, in some respects, has achieved some success, but also suffered a number of bottlenecks, such as regulatory policy confusion,
lack of communication content, communication technology is lagging behind the lack of professional mobile TV professionals, the use of tariff The high technical standards are not uniform and other
bottlenecks. Regulatory policy confusion. But the area out of the shielding range will not be affected by cell phone jammer .
Management regulations in the telecommunications or radio and television and the management of the mobile TV business clearly defined, the Ministry of Industry and SARFT there mobile TV The
controversy led by whom. In order to capture this emerging mobile TV market high ground, handset manufacturers, telecom operators, radio and television operators have joined the field, the media to
be outdone involved. In accordance with the relevant provisions of the Administration of Radio, all those engaged in online audio and video programs play unit must apply to the Radio and Television
Information Network 09016475 "introduced by the end of 2000, the Telecommunications Ordinance expressly provides image transmission is also a telecommunications areas The former belongs to the
administrative provisions, while the latter is the national laws and regulations. cell phone jammer is developed and manufactured on the basis of the existing product.
The two cross-cutting policies and regulations so that the regulatory policies of the mobile TV 17 confusion. Chaotic regulatory policy also caused a conflict of interest between different
departments, can not reach a consistent understanding of the operating mode of the mobile TV standards, and not within the legal and institutional framework for effective coordination of
broadcasting and telecommunications, and rural development, therefore very make life difficult for the development of mobile TV to create a stable communication environment, hinder the development
process of mobile TV. Secondly, the chaotic regulatory policy to the mobile TV services to carry out the obstacles. For example, some wishing to launch mobile TV service company, to get the mobile
TV business license must apply to the different authorities. cell phone jammer cab be validly used in the prison, detention house, labor camp and so on.The design of cell phone jammer is totally
developed by the nation
Read More..
band, CDMA frequency band and 3G frequency band at the same time.
And broadcasting 24 hours. Fourth, the development prospects of Chinas mobile TV and countermeasures of Chinas mobile TV prospects for the development and Countermeasures 4.1 bottlenecks in the
development of mobile TV to the diverse needs of the audience on the mobile terminal is gradually increasing, making the mobile TV market has shown signs of the trend gaining momentum, the future
can not Limited. Country in the process of development of mobile TV, in some respects, has achieved some success, but also suffered a number of bottlenecks, such as regulatory policy confusion,
lack of communication content, communication technology is lagging behind the lack of professional mobile TV professionals, the use of tariff The high technical standards are not uniform and other
bottlenecks. Regulatory policy confusion. But the area out of the shielding range will not be affected by cell phone jammer .
Management regulations in the telecommunications or radio and television and the management of the mobile TV business clearly defined, the Ministry of Industry and SARFT there mobile TV The
controversy led by whom. In order to capture this emerging mobile TV market high ground, handset manufacturers, telecom operators, radio and television operators have joined the field, the media to
be outdone involved. In accordance with the relevant provisions of the Administration of Radio, all those engaged in online audio and video programs play unit must apply to the Radio and Television
Information Network 09016475 "introduced by the end of 2000, the Telecommunications Ordinance expressly provides image transmission is also a telecommunications areas The former belongs to the
administrative provisions, while the latter is the national laws and regulations. cell phone jammer is developed and manufactured on the basis of the existing product.
The two cross-cutting policies and regulations so that the regulatory policies of the mobile TV 17 confusion. Chaotic regulatory policy also caused a conflict of interest between different
departments, can not reach a consistent understanding of the operating mode of the mobile TV standards, and not within the legal and institutional framework for effective coordination of
broadcasting and telecommunications, and rural development, therefore very make life difficult for the development of mobile TV to create a stable communication environment, hinder the development
process of mobile TV. Secondly, the chaotic regulatory policy to the mobile TV services to carry out the obstacles. For example, some wishing to launch mobile TV service company, to get the mobile
TV business license must apply to the different authorities. cell phone jammer cab be validly used in the prison, detention house, labor camp and so on.The design of cell phone jammer is totally
developed by the nation
Safe Constant Current Source Circuit Diagram
In the Safe Constant Current Source Circuit Diagram shown, a CMOS op amp controls the current through a p-channel HEXFET power transistor to maintain a constant voltage across RL The current is given by: 1 ~ VREF/Rl. The advantages of this configuration are: (a) in the event of a component failure, the load current is limited by Rl; and (b) the overhead voltage needed by the op amp and the HEXFET is extremely low.
Safe Constant Current Source Circuit Diagram
Friday, December 27, 2013
Single Supply fault Monitor Circuit Diagram
This Single Supply fault Monitor Circuit Diagram shows a typical over/under-voltage fault monitor for a single supply. The upper trip points, controlling OUT 1, are centered on 5.5 V with 100 mY of hysteresis Wu = 5.55 V, `L = 5.45 V); and the lower trip points, controlling OUT 2, are centered on 4.5 V, also with 100 mV of hysteresis. OUT 1 and OUT 2 are connected together in a wired OR configuration to generate a power OK signal.
Single Supply fault Monitor Circuit Diagram
Wednesday, December 25, 2013
Environmentally Friendly Mosquito Repeller
With the return of the fine weather, you’ll doubtless be enjoying lazing around of an evening on your patio or in your garden, but even if you’re not surrounded by marshes or other shallow water it’s very likely some intruding mosquitoes will come along to spoil this idyllic scene. Although indoors it’s easy to get rid of them these days, indeed even to prevent them coming into the house, the same can’t be said for the great outdoors.
We might mention the well-known Chinese coils – the only thing Chinese about them is undoubtedly their name – which very often drive people away as much as mosquitoes, if not more! Moreover they are nasty things to handle. There are also UV (ultra-violet) ‘electrocutors’ consisting of a blue lamp surrounded by two closely-spaced grilles between which a high voltage is applied. The mosquitoes (and fies and other flying insects) are supposedly attracted by the color of the lamp and as they approach, get electrocuted in contact with the two grilles.
The only thing you have to do is pull out the drawer from time to time and get rid of the mass of dead insects. Even though the effectiveness of these first two products remains questionable, it is less so than the one we’re nonetheless going to describe here. We’re talking about an ultrasonic mosquito repellent.
The principle, as described by its numerous promoters, is as follows. Only the female mosquitoes bite (that at least is an undisputed scientific fact) and they bite when they need to feed, and above all, to feed their eggs. In this situation, they seek to avoid the males whose ‘job’ has already been done, and so they fy away from the frequencies emitted by the males when they are on heat. This is where opinions now diverge.
According to certain publications, the frequency emitted by the male mosquitoes is said to be around 20–25 kHz, and so within the realm of ultrasound. But according to others, it is in the region of 5–7 kHz instead; frequencies that a human ear, even an elderly one, can still hear very well. Rather than spending lots of money (of the order of tens of pounds) buying such a device, which moreover generally have a fixed frequency, we’re suggesting building one yourself so that you can carry out your own research this summer, especially since the circuit proposed is very simple and cheap to build.
As the figure shows, it uses just a single IC, a CMOS type 4047. This very multi-purpose IC can be wired in very many operating modes, including that of the multivibrator or astable used here. The operating frequency is set by the external components C1, R1, and P1; the latter makes it possible to slightly adjust the frequency, given the uncertainty that exists over the most efective value…To best reproduce the high frequencies produced by the generator, the output transducer used is a simple tweeter, but it must be a piezo one.
Such a tweeter behaves in fact much like a capacitor, and so doesn’t overload the CMOS IC outputs that are incapable of supplying a substantial current, as everyone knows who’s ever worked with 400 series CMOS logic. To obtain an output signal of sufficient amplitude while being powered from a single 9 V battery, this tweeter is connected between the 4047’s Q and Q outputs, making it possible to apply complementary (antiphase) signals to the tweeter so it ‘sees’ an alternating voltage of double the supply voltage.
In purely theoretical terms, this quadruples the output power available. In practice, it’s better to regard it as tripling it, but the beneft achieved by doing it this way is nonetheless very real. All that remains is for you to place the project in the middle of the patio table or beside your lounger in order to get a taste of the calm of a summer’s evening without mosquitoes bothering you acoustically or worse, biting. At any rate, that’s what we wish for you…
Read More..
We might mention the well-known Chinese coils – the only thing Chinese about them is undoubtedly their name – which very often drive people away as much as mosquitoes, if not more! Moreover they are nasty things to handle. There are also UV (ultra-violet) ‘electrocutors’ consisting of a blue lamp surrounded by two closely-spaced grilles between which a high voltage is applied. The mosquitoes (and fies and other flying insects) are supposedly attracted by the color of the lamp and as they approach, get electrocuted in contact with the two grilles.
The only thing you have to do is pull out the drawer from time to time and get rid of the mass of dead insects. Even though the effectiveness of these first two products remains questionable, it is less so than the one we’re nonetheless going to describe here. We’re talking about an ultrasonic mosquito repellent.
The principle, as described by its numerous promoters, is as follows. Only the female mosquitoes bite (that at least is an undisputed scientific fact) and they bite when they need to feed, and above all, to feed their eggs. In this situation, they seek to avoid the males whose ‘job’ has already been done, and so they fy away from the frequencies emitted by the males when they are on heat. This is where opinions now diverge.
According to certain publications, the frequency emitted by the male mosquitoes is said to be around 20–25 kHz, and so within the realm of ultrasound. But according to others, it is in the region of 5–7 kHz instead; frequencies that a human ear, even an elderly one, can still hear very well. Rather than spending lots of money (of the order of tens of pounds) buying such a device, which moreover generally have a fixed frequency, we’re suggesting building one yourself so that you can carry out your own research this summer, especially since the circuit proposed is very simple and cheap to build.
As the figure shows, it uses just a single IC, a CMOS type 4047. This very multi-purpose IC can be wired in very many operating modes, including that of the multivibrator or astable used here. The operating frequency is set by the external components C1, R1, and P1; the latter makes it possible to slightly adjust the frequency, given the uncertainty that exists over the most efective value…To best reproduce the high frequencies produced by the generator, the output transducer used is a simple tweeter, but it must be a piezo one.
Such a tweeter behaves in fact much like a capacitor, and so doesn’t overload the CMOS IC outputs that are incapable of supplying a substantial current, as everyone knows who’s ever worked with 400 series CMOS logic. To obtain an output signal of sufficient amplitude while being powered from a single 9 V battery, this tweeter is connected between the 4047’s Q and Q outputs, making it possible to apply complementary (antiphase) signals to the tweeter so it ‘sees’ an alternating voltage of double the supply voltage.
In purely theoretical terms, this quadruples the output power available. In practice, it’s better to regard it as tripling it, but the beneft achieved by doing it this way is nonetheless very real. All that remains is for you to place the project in the middle of the patio table or beside your lounger in order to get a taste of the calm of a summer’s evening without mosquitoes bothering you acoustically or worse, biting. At any rate, that’s what we wish for you…
B. Broussas
Elektor Electronics 2008
Elektor Electronics 2008
Tuesday, December 24, 2013
Simple Voltage Multiplier Circuit Diagram
This is a Simple Voltage Multiplier Circuit Diagram. This Simple Voltage Multiplier Circuit Diagram we build to day. how to build lets start. Figure 99-l(a)`s circuit exhibits a high-output impedance as a result of the small effective capacitance of the series-connected capacitors, and it exhibits considerable voltage loss due to all of the diode drops. Further, this circuit requires 2 diodes and 2 capacitors to produce a dc output voltage approximately times the rail voltage. Figure 99-1 (b)`s circuit multiplies more effectively using fewer diodes and capacitors.
Simple Voltage Multiplier Circuit Diagram
The parallel arrangement of the capacitors lets you use smaller capacitors than those required in Fig. 99-1(a). Alternatively, when using the same capacitor values of Fig. 99-1 (a), the output impedance will be lower. Whereas the clock source directly drives only one of the two strings of capacitors in Fig. 99-1(a), Fig. 99-l(b)`s clock drives both strings with opposite phases.
This drive scheme doubles the voltage per stage of two diodes. A final diode is necessary to pick off the dc output voltage because both strings of capacitors now carry the - p ac input-voltage waveform. The ICL7667 dual-FET driver accepts a TTL drive swing and provides a low-impedance push-pull drive to the diode string. This low impedance is particularly helpful when using a long string to raise output voltage to more than 100 V, starting from a low rail voltage.
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