Monostable circuit

Welcome to free circuit dot com,For the last article in this series, we may be unstable a cycle which has no stable output state. In this post circuit we will show the monostable circuit, which has a stable state.

The waveforms in Figure 1 show the effect of a monostable. A monostable circuit produces a pulse of a certain length (time T) in response to a trigger input such as a pushbutton. The output of the circuit remains in the low position to a trigger input, does the name “Mono”, “stable condition”.

This type of circuit is ideal for use in a “push-to-operate” in a model system for exhibitions. A visitor can press a button to a model mechanism in motion, and the mechanism will automatically after a certain time. Another use of the circuit “the bounce” an important contribution to a digital IC – this application will be explained later in this article.

infrared detector circuit

Welcome again ,Free circuit dot com have the circuit can be used as an infrared beam barrier and a proximity detector.
The circuit uses the very popular Sharp IR module (Vishay module can also be used). NOS pin. circuit is shown in the Sharp and Panasonic modules. For other modules please refer to the relevant datasheets.
The receiver consists of a 555 timer IC working as an oscillator at about 38Khz (also works from 36kHz to 40kHz), which must be configured using the standard 10K. The duty cycle of the IR beam is about 10%. This allows us to more current through the LED, allowing a greater range.
The receiver uses a sharp IR unit. If the IR beam from the transmitter IR drops, the output is activated, which activates the relay and turns off when the beam is blocked. The relay contacts can be used to turn ON / OFF alarm, lights etc. The 10K advance should be adjusted until the receiver detects the IR beam.

The circuit can also be used as a proximity sensor that objects in front of the device detects without obstructing a IR beam. So the LED has the same direction as the IR module and at the same level. The proposed scheme is shown in diagram. The LED should be adequately covered with a reflective material like glass or aluminum plates on the sides to stop the spread of the IR beam to prevent and get a sharp focus the beam.
When there is nothing for them, the IR beam reflected on the unit and therefore the circuit is not activated. When an object comes near the device, the infrared light from the LED reflected from the object on the unit and therefore the circuit is activated.

If there is still a very bad start, use a 1uF or higher capacitor instead of the 0.47uF.

555 Negative Voltage Generator Circuit

This circuit is power supplies for your hobby project. I have frequent requests for help which indicates that there is often a need to generate a negative voltage RS-232 or other circuits, such as when there are only 5 or 12 volt source that is readily available. I encountered the same problem. There are answers available in trade with these problems, but they are generally bulky, expensive and not readily available when needed, and are not really adaptable to any situation.
For me, the solution came as a draft in the IC 555 back late 70 Sec.  and early 80 Sec. a negative voltage generator quickie. There is nothing new or particularly clever about the design based on one of the most popular channels and versatile product ever. The parties are plentiful and cheap, two of my criteria for DIY projects, in general, they are all part of a junk e-box studio. The circuit is very simple and easily adaptable to different requirements. The circuit can be used to generate twice the supply voltage reverses the polarity of the diode and output capacitor.

Xenon strobe circuit A

Circuit source voltage high-light Xenon Strobe with this circuit using the power source DC Size 3V-6V with IC LM555 acts produce frequencies and cycles in nature PWM and then through the MOSFET driver transformers, high voltage can be 220V, then left through a series circuit Flash. The left driving lamp reflector.

Xenon strobe circuit B

network cable tester circuit

It works for network, telephone, cable with RJ45 half “Registered Jack” plug immediately indicate whether a crossover network cable or straight, flashing a yellow or green LED. If something is broken or if you press the button, the tester is in line with the wire test.

network cable tester diagram

How does it work?

The top RJ45 connector sends signals to each of its eight legs. The lower RJ45 connector receives signals from the top RJ45 connector created by the wire. When the red LED above the orange light LED bar shows the pins in the top RJ45 connector sends a test signal, and when the bottom of the red LED illuminates orange LED bar indicates which of the eight dioceses of the bottom RJ45 connector signal receives in this state where the wire is broken or not connected, none of LEDs in the LED bar will light up orange. If a short circuit between two or more wires, more than an orange LED lights up when the bottom red LED lights. Each time the button is the active output pin.

 Specification
For network cable (RJ45) and telephone (RJ11) tests.
Similar test can double-twisted cables 1,2,3,4,5,6,7,8 and Ground, meanwhile, can judge wrong connection, short circuit and open circuit.
ON / OFF button.
With four LED indicator.
Composing the master and remote two tests that can take a role in the testing easier.
Power by 9V battery.
Compact, durable design with a black plastic bag with zipper for storage.
Cable RJ45 network and RJ11 phone port

Xenon Strobe CIRCUIT 1

The circuit used to come in kit form with a surplus supplier, but it is probably more available. It shows some new concepts such as using a 555 as a pulse width modulator (PWM), and serial / parallel processors flash camera.
The 555 is mounted as a pulse width modulator (from the (low) time to be determined by the regulator). The output on pin 3 is connected to the gate of P-channel MOSFET (IRF9Z20) through the 100R resistor to prevent parasitic oscillation of the transistor. A low signal on pin 3 causes the MOSFET to turn, so the button controls the flash output and a bit rate, by varying the duty cycle of 555 and in turn the MOSFET.

Xenon Strobe CIRCUIT 2

Time Delay Relay with IC555 circuit

Parts List

C1    10uf 16V Electrolytic Capacitor
C2         0.01uf Ceramic Disc Capacitor
R1           1  Meg Pot
R2       10 K 1/4 Watt Resistor
D1,D2        1N914 Diodes
U1         555 Timer IC
RELAY          9V Relay
S1          Normally Open Push Button Switch

Remark:
1. We used R1 adjusts the on time.

2. You can get a different capacitor for C1 to change the maximum on time.

3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.

9 Sec. Timer control Relay circuit

IC 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower trigger point, or about 3 Vdc. 

That time the switch is opened, the transistor in parallel with the timing capacitor (22uF) is shut off allowing the capacitor to begin charging and the IC 555 timer circuit to produce an approximate one second clock signal to the decade counter. The counter advances on each positive going change at pin 14 and is enabled with pin 13 terminated low. When the 9th count is reached, pin 11 and 13 will be high, stopping the counter and energizing the relay. Longer delay times can be obtained with most capacitor or most resistor at pins 2 and 6 of the IC 555 timer

 

 brightness - With used 40 LEDs, We can fill the taillight evenly with light, thereby making the most of the limited area I’ve got.
Higher brightness – I can make the brake light brighter than stock.
Lower power – At maximum brightness (which I won’t use), this light takes 10 Watts — less than the 18 Watts the normal taillight takes.

 Format

Circuit & Step by Step to build it –>

40 LED bicycle Tail Light Circuit

DIY: Step by Step

Step 1

Cutting the blank PC board. The template shows two patterns – the one on the left is for 12x 3W LEDs, which would have been twice as brite!

Step 2

Step 2 : 3M Reflective tape applied behind LEDs.

Step 3

 Step3 : Cutting to fit — 3M Reflective tape applied behind LEDs. 

Step 4.

 Step4 :

Step 5 ut the resistor and soldering.

Step 7

The narrow-angle LEDs make up the two brighter spots.

40 LED bicycle tail light.