Long-Interval Pulse Generator Circuit Diagram

A rectangular-wave pulse generator with an extremely long period can be built using only two components: a National Semiconductor LM3710 supervisor IC and a 100-nF capacitor to eliminate noise spikes. This circuit utilises the watchdog and reset timers in the LM3710. The watchdog timer is reset when an edge appears on the WDI input (pin 4). If WDI is continuously held at ground level, there are not any edges and the watchdog times out. After an interval TB, it triggers a reset pulse with a duration TA and is reloaded with its initial value. The cycle then starts all over again. As a result, pulses with a period of TA + TB are present at the RESET output (pin 10).

Long-Interval Pulse Generator Circuit Diagram

 Long-Interval Pulse Generator Circuit Diagram

As can be seen from the table, periods ranging up to around 30 seconds can be achieved in this manner. The two intervals TA and TB are determined by internal timers in the IC, which is available in various versions with four different ranges for each timer. To obtain the desired period, you must order the appropriate version of the LM3710. The type designation is decoded in the accompanying table. 

The reset threshold voltage is irrelevant for this particular application of the LM3710. The versions shown in bold face were available at the time of printing. Current information can be found on the manufacturer’s home page (www.national.com). The numbers in brackets indicate the minimum and maximum values of intervals TA and TB for which the LM3710 is tested. The circuit operates with a supply voltage in the range of 3–5 V.

Source by : Streampowers

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2 Watt FM Transmitter Circuit Diagram

CIRCUIT DESCRIPTION

The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit.

Components List

R1=220K R2=4.7K R3,R4=10K R5=100ohm

C1,C2=4.7uF Electrolytic C3,C4=1nF C5=2-15pF C6=3.3pF

Q1=BC547C Q2=BD135 P1=25K MIC=Electret Condenser Type

P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils link

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Medium-Wave Modulator Circuit Diagram

If you insist on using a valve radio and listening to medium-wave stations, you have a problem: the existing broadcasters have only a limited number of records. Here there’s only one remedy, which is to build your own medium-wave transmitter. After that, you can play your own CDs via the radio. 

The transmitter frequency is stabilised using a 976-kHz ceramic resonator taken from a TV remote control unit. Fine tuning is provided by the trimmer capacitor. If there’s another station in the background, which will probably be weak, you can tune it to a heterodyne null, such as 981 kHz. As an operator of a medium-wave transmitter, that’s your obligation with respect to the frequency allocations. And that’s despite the fact that the range of the transmitter is quite modest. The small ferrite coil in the transmitter couples directly into the ferrite rod antenna in the radio. 

Medium-Wave Modulator Circuit Diagram

The modulator is designed as an emitter follower that modulates the supply voltage of the output amplifier. As the medium-wave band is still mono, the two input channels are merged. The potentiometer can be adjusted to obtain the least distortion and the best sound. The RF amplifier stage has intentionally been kept modest to prevent any undesired radiation. The quality of the output signal can also be checked using an oscilloscope. Clean amplitude modulation should be clearly visible. 

The medium-wave modulator can simply be placed on top of the radio. A signal from a CD player or other source can be fed in via a cable. Now you have a new, strong station on the radio in the medium-wave band, which is distinguished by good sound quality and the fact that it always plays what you want to hear. 

Author: Burkhard Kainka - Copyright: Elektor

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Radio only 1 transistor without electricity

Experts and amateurs have been Experimenting with radios without batteries since the wireless communication started.

In many designs we've seen radios that operate without power, but all are known to use the diode 1N34. (Crystal Radio).

Although significant improvements have increased the sensitivity and selectivity of these system circuits, Performances were limited until new techniques have emerged. 
 
Here we have the first transistor radio that works without batteries, it is powered by random electric fields are everywhere in the atmosphere. 

These circuits are relatively cheap to manufacture, have more volume and better reception from the crystal radios.
 This circuit is a medium wave receiver and attaches easily to frequencies from 500Khz to 11Mhz.
To get good results in the reception of radio stations, we should give great importance to the ground and the antenna.
To listen to distant and weak stations we have to use a battery 9volt parallel with the capacitor C4 with it's positive side between R2 and C4.
The coils are in the frequency of 500-1500Khz is tight and closely wrapped.
The coils are in frequency of 1.5-11Mhz is more tighter and more closely wrapped.

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Data accretion System Circuit Diagram

In this circuit, an HA-4900 series comparator is used in conjunction with a D/A converter to form a simple,

Data accretion System Circuit Diagram

versatile, multichannel analog input for a data acquisition system. The processor first sends an address to the D/A, then the processor reads the digital word generated by the comparator outputs, lb perform a simple comparison, the processor sets the D/A to a given reference level, then examines one or more comparator outputs to determine if the inputs are above or below the reference. A window comparison consists of two such cycles with two reference levels set by the D/A. One way to digitize the inputs would be for the processor to increment the D/A in steps. The D/A address, as each comparator switches, is the digitized level of the input. While stairstepping, the D/A is slower than successive approximation; all channels are digitized during one staircase ramp.

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Pulse Charger for reviving tired Lead Acid batteries

Build a Pulse Charger for reviving tired Lead Acid batteries circuit diagram. If you own a motorcycle, a motor home, a caravan, a lawn mover, a day cruiser or maybe a vintage car you must at some point had to write off a lead acid battery. When a battery is improperly charged or allowed to self-discharge as occurs during non-use, sulphate crystals build up on the battery's plates. The sulphate preventing the battery from being fully charged and therefore it is unable to deliver its full capacity. When trying to charge a battery in this state it only gets hot and looses water, the gravity of the electrolyte is not increasing to its normal “full charge” state. 

 Pulse Charger for reviving tired Lead Acid batteries Circuit Diagram

The only thing you do is killing the battery completely. If a battery has a resting voltage of at least 1.8 Volts/cell and no cells are shorted, desalination of its plates can be done. This circuit is an add-on and part for a modification of a normal charger and it takes care of the sulphate problem.

The project: get hold of an old charger, big or small it’s your choice depending on the size of batteries you normally handle (bigger is better). There are some tricks to boost the performance if you need it. Start by ripping out everything except the transformer and the rectifier. Some older chargers are equipped with fin rectifiers, which have high voltage drop and must be replaced. Replace with a rugged bridge rectifier that can cope with the amperes. All wiring on secondary should be short and heavy wire. The rectifier should be bolted to the chassis to keep cool. If the charger have a high/low switch it’s a bonus, if not you can in some cases add a few turns of wire on the secondary winding. 

The circuit; a 14-stage ripple counter and oscillator IC 4060 produce a pulse, which is the heartbeat of the circuit. The pulse is feed to the 555 timer that deicide the length of the active output. With the switch you can select long or short pulse output. The output of the 555 timer triggers the zero-cross opt isolator triac driver MOC 3041 via a transistor. This gives the charger transformer a soft start via the triac and the snubber circuit. A small power supply is necessary for the circuit and consists of T1 a transformer 15V 0.1A secondary, a bridge rectifier, a regulator and two caps. Because this project include a charger that is (X) the outcome can differ in performance from one case to another. However this do not mean that your project doesn’t work, but the efficiency can vary. Some notes the snubbercap is a high voltage AC type (X) and the resistors on the mains side is at least 0.5W type. Use a triac that can take 400V+ and 10A+, I use BTA 25.600 but this is overkill in most cases. No PCB sorry!

How it works:
Well the short version. The object is to get the cell voltage high enough for the sulphate to dissolve without boiling or melting the battery. This is achieved by applying higher voltage for shorter periods and let the battery rest for a while. The pulses on short range is about 0.5s on / 3s off and the long pulse range is 1.4s on / 2s off. These times can vary depending on component tolerances. Start on long pulse and if you discover “boiling” (more than with normal charging) in the electrolyte switch to short puls. Don’t leave the process unattended, at least until you know how your specific version of this project turns out. I built ver.1 of this circuit some 10 years ago and have experimented with it but I’m sure someone can improve it further.

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Build a Cmos line Receiver Circuit Diagram

Build a Cmos line Receiver Circuit Diagram. This is a simple  Cmos line Receiver Circuit Diagram, in this circuit the trip point is set half way between the supplies by Rl and R2; R3 provides over 200 mV of hysteresis to increase noise immunity. Maximum frequency of operation is about 300 kHz. If response to TTL levels is desired, change R2 to 39 K. The trip point is now centered at 1 V.

Cmos line Receiver Circuit Diagram

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Build a Power Pulse Using by LM350 and NE555 Circuit Diagram

This is a Simple Power Pulse Using by LM350 and NE555 Circuit Diagram. This circuit can use to drive lamp,power LED,DC motor etc. Adjust R5 for output amplitude.Adjust R1 for output power .

Power Pulse Circuit Diagram

The LM350 is adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 3A over a 1.2V to 33V output range.This circuit requires 5-15V power supply.

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