Showing posts with label circuit. Show all posts
Showing posts with label circuit. Show all posts
Friday, January 10, 2014
Simple Unipolar to Dual Supply Converter Circuit Diagram
Simple Unipolar to Dual Supply Converter Circuit Diagram. 817V The outputs in this circuit are independently variable and can be loaded unsymmetrically. The output voltage remains constant, irrespective of load and changes. By varying potentiometers R2 or R6, the output voltages can be conveniently set. Outputs can be varied between 8 and 17 V, so that the standard ±9, ±12, and ±15 V settings can be made.
Unipolar to Dual Supply Converter Circuit Diagram
This converter is designed for a maximum load current of 1 A and the output impedance of both supplies of 0.35 0. This circuit is not protected against shortcircuits, but uses the protection provided by the de input source. This circuit is ideal for biassing operation amplifier circuits.
Friday, December 27, 2013
Build a 10 Amp 13 8 Volt Power Supply Circuit Diagram
Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to troubleshoot and repair other power supply units in the shack. It should be noted that there is no real cost advantage to building your own power supply unless you can get a large power transformer and heat sink for a super low price.
Of course rolling our own gives us the ability to customize the circuit and make it even more reliable than commercial units. The circuit in Figure 1 will give us 10 amps (12 amps surge) with performance that equals or exceeds any commercial unit. The circuit even has a current limiting feature which is a more reliable system than most commercial units have. Just like other commercial units, this circuit uses the LM723 IC which gives us excellent voltage regulation. The circuit uses 3 pass transistors which must be heat sinked. Resistor R9 allows the fine tuning of the voltage to exactly 13.8 volts and the resistor network formed by resistors R4 through R7 controls the current limiting.
The LM723 limits the current when the voltage drop across R5 approaches .7 volts. To reduce costs, most commercial units rely on the HFE of the pass transistors to determine the current limiting. The fault in that system is that the HFE of the pass transistors actually increases when the transistors heat up and risks a thermal runaway condition causing a possible failure of the pass transistors. Because this circuit samples the collector current of the pass transistors, thermal runaway is not a problem in this circuit making it a much more reliable power supply.
The only adjustment required is setting R9 to the desired output voltage of anywhere between 10 and 14 volts. You may use a front panel mounted 1K potentiometer for this purpose if desired. Resistor R1 only enhances temperature stability and can be eliminated if desired by connecting pins 5 and 6 of IC-1 together. Although it really isn’t needed due to the type of current limiting circuit used, over voltage protection can be added to the circuit by connecting the circuit of Figure 2 to Vout. The only way over voltage could occur is if transistors Q2 or Q3 were to fail with a collector to emitter short. Although collector to emitter shorts do happen, it is more much more likely that the transistors will open up when they fail.
10 Amp 13.8 Volt Power Supply Circuit Diagram
I actually tested this and purposely destroyed several 2N3055’s by shorting the emitters to ground. In all cases the transistors opened up and no collector to emitter short occurred in any transistor. In any event, the optional circuit in Figure 2 will give you that extra peace of mind when a very expensive radio is used with the power supply. The circuit in Figure 2 senses when the voltage exceeds 15 volts and causes the zener diode to conduct. When the zener diode conducts, the gate of the SCR is turned on and causes the SCR to short which blows the 15 amp fuse and shuts off the output voltage.
A 2N6399 (Tech America) was used for the SCR in the prototype but any suitable SCR can be used. While over voltage protection is a good idea, it should not be considered a substitute for large heat sinks. I personally feel the best protection from over voltage is the use of large heat sinks and a reliable current limiting circuit. Be sure to use large heat sinks along with heat sink grease for the 2N3055 transistors. I have used this power supply in my shack for several months on all kinds of transceivers from HF, VHF to UHF with excellent results and absolutely no hum. This power supply will be a welcome addition to your shack and will greatly enhance your knowledge of power supplies.
Parts
R1 1.5K ¼ Watt Resistor (optional, tie pins 6 & 5 of IC1 together if not used.)
R2,R3 0.1 Ohm 10 Watt Resistor (Tech America 900-1002)
R4 270 Ohm ¼ Watt Resistor
R5 680 Ohm ¼ Watt Resistor
R6,R7 0.15 Ohm 10 Watt Resistor (Tech America 900-1006)
R8 2.7K ¼ Watt Resistor
R9 1K Trimmer Potentiometer (RS271-280)
R10 3.3K ¼ Watt Resistor
C1,C2,C3,C4 4700 Microfarad Electrolytic Capacitor 35 Volt (observe polarity)
C5 100 Picofarad Ceramic Disk Capacitor
C6 1000 Microfarad Electrolytic Capacitor 25 Volt (observe polarity)
IC1 LM723 (RS276-1740) Voltage Regulator IC. Socket is recommended.
Q1 TIP3055T (RS276-2020) NPN Transistor (TO-220 Heat Sink Required)
Q2,Q3 2N3055 (RS276-2041) NPN Transistor (Large TO-3 Heat Sink Required)
S1 Any SPST Toggle Switch
F1 3 Amp Fast Blow Fuse
D1-D4 Full Wave Bridge Rectifier (RS276-1185)
T1 18 Volt, 10 Amp Transformer Hammond #165S18 (Tech America 900-5825)
R1 1.5K ¼ Watt Resistor (optional, tie pins 6 & 5 of IC1 together if not used.)
R2,R3 0.1 Ohm 10 Watt Resistor (Tech America 900-1002)
R4 270 Ohm ¼ Watt Resistor
R5 680 Ohm ¼ Watt Resistor
R6,R7 0.15 Ohm 10 Watt Resistor (Tech America 900-1006)
R8 2.7K ¼ Watt Resistor
R9 1K Trimmer Potentiometer (RS271-280)
R10 3.3K ¼ Watt Resistor
C1,C2,C3,C4 4700 Microfarad Electrolytic Capacitor 35 Volt (observe polarity)
C5 100 Picofarad Ceramic Disk Capacitor
C6 1000 Microfarad Electrolytic Capacitor 25 Volt (observe polarity)
IC1 LM723 (RS276-1740) Voltage Regulator IC. Socket is recommended.
Q1 TIP3055T (RS276-2020) NPN Transistor (TO-220 Heat Sink Required)
Q2,Q3 2N3055 (RS276-2041) NPN Transistor (Large TO-3 Heat Sink Required)
S1 Any SPST Toggle Switch
F1 3 Amp Fast Blow Fuse
D1-D4 Full Wave Bridge Rectifier (RS276-1185)
T1 18 Volt, 10 Amp Transformer Hammond #165S18 (Tech America 900-5825)
Thursday, December 26, 2013
Part 2 High Voltage Supply Circuit Diagram
This High-Voltage Supply Circuit Diagram uses a transistor oscillator and a voltage multiplier to charge CIO and CI 1 to a high voltage. When the spark gap breaks down, T2 produces a high-voltage pulse via the capacitance discharge of CIO and Cll into its primary. T2 is an auto ignition coil.
Read : High-Voltage Pulse Supply Circuit Diagram
Read : High-Voltage Pulse Supply Circuit Diagram
High-Voltage Supply Circuit Diagram
Wednesday, December 25, 2013
Simple Dc Ac Inverter Circuit Diagram
This dc-to-ac inverter is based on the popular 555. A 555 oscillator circuit drives a buffer amplifier consisting of Ql, Q2, and Q3.
The circuit operates at 150 to 160 Hz. Tl can be a 6.3-V or 12.6-V filament transformer as applicable.The frequency can be changed by changing the values of Rl and/or Cl.
Simple Dc/Ac Inverter Circuit Diagram
Monday, December 23, 2013
Simple RF Transmitter for PIR Sensors Circuit Diagram
This is the Simple RF Transmitter for PIR Sensors Circuit Diagram.
Sunday, December 22, 2013
Simple 2304 and 3456 MHz Power Amplifiers Circuit Diagram
This is a Simple 2304 and 3456 MHz Power Amplifiers Circuit Diagram
Thursday, December 19, 2013
Simple Automatic Water Pump Controller Circuit Diagram
Simple Automatic Water Pump Controller Circuit Diagram is a series of functions to control the Automatic Water Pump Controller Circuit in a reservoir or water storage. As the water level sensor made with a metal plate mounted on the reservoir or water tank, with a sensor in the short to create the top level and a detection sensor for detecting long again made the lower level and ground lines connected to the bottom of reservoirs or reservoir.
The series of automatic water pump controller is designed with 2 inputs NOR by 4 pieces and relay that is activated by the transistor. Automatic water pump circuit requires +12 VDC voltage source and can be used to control the water pump is connected to AC power . Here is the complete series of pictures.
Automatic Water Pump Controller Circuit Diagram
working principle series of automatic water pump controller above is. At the time the water level is below both sensors, the output IC1C (pin 10) will be LOW, Kemudin when the water began to touch the lower level sensor, the output IC1C (pin10) remains LOW until the water touches the sensor level above, then the output IC1C (pin 10) going HIGH and active relay through Q1 and turn on the water pump to meguras reservoir.
At the muli down and water level sensors for water untouched MKA IC1C output (pin 10) remains HIGH until the new water untouched semuasensor IC1C output (pin 10) LOW and water pump died. The series of automatic water pump controller is equipped with SW1 which serves to reverse the logic of drains (the output of IC1C) and the concept of water supplied (output dri IC1D).
When SW1 is connected to IC1D the water pump will turn on when the water does not touch all the sensors and will die when all the sensors tesentuh water. Automatic water pump controller can be used to fill or drain the water according to which mode is selected via SW1.
List Component Automatic Water Pump Controller
R1 = 15K
R2 = 15K
R3 = 10K
R4 = 1K
D1 = LED
D2 = 1N4148
Q1 = BC337
IC1 = 4001
SW = SPDT Switches
Relay RL1 = 12V
Tuesday, September 24, 2013
MP3 FM Transmitter Circuit Diagram
Heres a simple VHF FM transmitter that could be used to play audio files from an MP3 player or computer on a standard VHF FM radio. The circuit use no coils that have to be wound. This FM transmitter can be used to listen to your own music throughout your home. When this FM transmitter used in the car, there is no need for a separate input to the car stereo to play back the music files from your MP3 player.
Project image :
To keep the circuit simple as well as compact, it was decided to use a chip made by Maxim Integrated Products, the MAX2606 [1]. This IC from the MAX2605-MAX2609 series has been specifically designed for low-noise RF applications with a fixed frequency. The VCO (Voltage Controlled Oscillator) in this IC uses a Colpitts oscillator circuit. The variable-capacitance (varicap) diode and feedback capacitors
for the tuning have also been integrated on this chip, so that you only need an external inductor to fix the central oscillator frequency.
for the tuning have also been integrated on this chip, so that you only need an external inductor to fix the central oscillator frequency.
t is possible to fine-tune the frequency by varying the voltage to the varicap. Not much is demanded of the inductor, a type with a relatively low Q factor (35 to 40) is sufficient according to Maxim. The supply voltage to the IC should be between 2.7 and 5.5 V, the current consumption is between 2 and 4 mA. With values like these it seemed a good idea to supply the circuit with power from a USB port.
Circuit diagram: 
Resistors (all SMD 0805)
R1,R2 = 22kΩ
R3 = 4kΩ7
R4,R5 = 1kΩ
R6 = 270Ω
P1 = 10kΩ preset, SMD (TS53YJ103MR10 Vishay Sfernice, Farnell # 1557933)
P2 = 100kΩ preset, SMD(TS53YJ104MR10 Vishay Sfernice, Farnell # 1557934)
Capacitors (all SMD 0805)
C1,C2,C5 = 4μF7 10V
C3,C8 = 100nF
C4,C7 = 2nF2
C6 = 470nF
Inductors
L1 = 390nF, SMD 1206 (LQH31HNR39K03L Murata, Farnell # 1515418)
L2 = 2200Ω @ 100MHz, SMD, common-mode choke, 1206 type(DLW31SN222SQ2L Murata, Farnell #1515599)
Semiconductors
IC1 = MAX2606EUT+, SMD SOT23-6 (Maxim Integrated Products)
Miscellaneous
K1 = 3.5mm stereo audio jack SMD (SJ1-3513-SMT
CUI Inc, DIGI-Key # CP1-3513SJCT-ND)
K2 = 5-pin header (only required in combination with 090305-I pre-emphasis circuit)
K3 = USB connector type A, SMD (2410 07 Lumberg, Farnell # 1308875)
A common-mode choke is connected in series with the USB connections in order to avoid interference between the circuit and the PC supply. There is not much else to the circuit. The stereo signal connected to K1 is combined via R1 and R2 and is then passed via volume control P1 to the Tune input of IC1, where it causes the carrier wave to be frequency modulated. Filter R6/C7 is used to restrict the bandwidth of the audio signal. The setting of the frequency (across the whole VHF FM broadcast band) is done with P2, which is connected to the 5 V supply voltage.
The PCB designed uses resistors and capacitors with 0805 SMD packaging. The size of the board is only 41.2 x 17.9 mm, which is practically dongle-sized. For the aerial an almost straight copper track has been placed at the edge of the board. In practice we achieved a range of about 6 metres (18 feet) with this. There is also room for a 5-way SIL header on the board. Here we find the inputs to the 3.5 mm jack plug, the input to P1 and the supply voltage. The latter permits the circuit to be powered independently from the mains supply, via for example three AA batteries or a Lithium button cell. Inductor L1 in the prototype is a type made by Murata that has a fairly high Q factor: minimum 60 at 100 MHz.
PCB Layout :
Take care when you solder filter choke L2, since the connections on both sides are very close together. The supply voltage is connected to this, so make sure that you don’t short out the USB supply! Use a resistance meter to check that there is no short between the two supply connectors before connecting the circuit to a USB port on a computer or to the batteries.
P1 has the opposite effect to what you would expect (clockwise reduces the volume), because this made the board layout much easier. The deviation and audio bandwidth varies with the setting of P1. The maximum sensitivity of the audio input is fairly large. With P1 set to its maximum level, a stereo input of 10 mVrms is sufficient for the sound on the radio to remain clear. This also depends on the setting of the VCO. With a higher tuning voltage the input signal may be almost twice as large (see VCO tuning curve in the data sheet). Above that level some audible distortion becomes apparent. If the attenuation can’t be easily set by P1, you can increase the values of R1 and R2 without any problems.
Measurements with an RF analyzer showed that the third harmonic had a strong presence in the transmitted spectrum (about 10 dB below the fundamental frequency). This should really have been much lower. With a low-impedance source connected to both inputs the bandwidth varies from 13.1 kHz (P1 at maximum) to 57 kHz (with the wiper of P1 set to 1/10). In this circuit the pre-emphasis of the input is missing. Radios in Europe have a built-in de-emphasis network of 50 μs (75 μs in the US). The sound from the radio will therefore sound noticeably muffled. To correct this, and also to stop a stereo receiver from mistakenly reacting to a 19 kHz component in the audio signal, an enhancement circuit Is published elsewhere in this issue (Pre-emphasis for FM Transmitter, also with a PCB). Author: Mathieu Coustans, Elektor Magazine, 2009
Notice. The use of a VHF FM transmitter, even a low power device like the one described here, is subject to radio regulations and may not be legal in all countries.
Source :http://fmtvguide.blogspot.com
Saturday, August 31, 2013
Nite Rider Lights Circuit
Circuit Diagram
The circuit is drawn with PCB 123 which you can download for free from http://www.pcb123.com
As a keen cyclist I am always looking for ways to be seen at night. I wanted something that was a novelty and would catch the motorists eye. So looking around at my fellow cyclists rear lights, I came up with the idea of NITE-RIDER. NINE extra bright LEDs running from left to right and right to left continuously. It could be constructed with red LEDs for use on the rear of the bike or white LEDs for an extra eye catcher on the front of the bike.
All ICs are CMOS devices so that a 9V PP3 battery can be used, and the current drawn is very low so that it will last as long as possible.
All ICs are CMOS devices so that a 9V PP3 battery can be used, and the current drawn is very low so that it will last as long as possible.
Parts
1 555 timer IC4.
1 4027 flip flop IC1.
2 4017 Decade Counter IC2 and IC3.
3 4071 OR gate IC5, IC6 and IC7.
1 470 Ohm resistor 1/4 watt R3.
2 10K resistors 1/4 watt R1 and R2.
1 6.8UF Capasitor 16V C1.
9 Super brght LEDs 1 to 9.
1 9V PP3 Battery.
1 single pole switch SW1.
1 Box.
1 555 timer IC4.
1 4027 flip flop IC1.
2 4017 Decade Counter IC2 and IC3.
3 4071 OR gate IC5, IC6 and IC7.
1 470 Ohm resistor 1/4 watt R3.
2 10K resistors 1/4 watt R1 and R2.
1 6.8UF Capasitor 16V C1.
9 Super brght LEDs 1 to 9.
1 9V PP3 Battery.
1 single pole switch SW1.
1 Box.
How The Circuit Works.
IC4, C1, R1 and R2 are used for the clock pulse which is fed to both the counters IC2 and IC3 Pin 14.
IC1 is a Flip Flop and is used as a switch to enable ether IC2 or IC3 at pin 13.
IC7a detects when ether IC2 or IC3 has reached Q9 of the counter pin 11.
IC5, IC6 and IC7a protects the outputs of the counters IC2 and IC3 using OR gates which is then fed to the Anodes of the
LEDs 1 to 9.
IC4, C1, R1 and R2 are used for the clock pulse which is fed to both the counters IC2 and IC3 Pin 14.
IC1 is a Flip Flop and is used as a switch to enable ether IC2 or IC3 at pin 13.
IC7a detects when ether IC2 or IC3 has reached Q9 of the counter pin 11.
IC5, IC6 and IC7a protects the outputs of the counters IC2 and IC3 using OR gates which is then fed to the Anodes of the
LEDs 1 to 9.
Tuesday, April 9, 2013
Up Down Timer Circuit For A Power Antenna
This up/down timer circuit was designed to control a power antenna on a late-model vehicle. Normally, this vehicle uses a body computer to control the antenna. However, the person who owned the vehicle wanted to install his own high powered audio stereo system. The original stereo system was tied in with the body computer and this meant that a separate antenna controller was required for the after-market sound system. Also, the power antenna fitted did not have limit switches inside, hence the need for a timed control circuit. Heres how the circuit works. first, assume that the radio antenna control output is not switched on - ie, the radio is switched off.
In that case, relay RLYC will be off and so relay RLYA will also be off, as is the motor. Conversely, when the radio is switched on, the radio antenna control output line switches to +12V. And when that happens, RLYC closes its contacts and applies power to the circuit. As a result, C2 (330OF) quickly charges via D4, while Q4 is biased on via D5 and R5. This ensures that Q3 and relay RLYB remain off. At the same time, Q2 is is turned on, thus turning on RLYA and applying power to the motor. This drives the antenna in the up direction. During this time, C1 charges via R2.
Circuit diagram:
Up/Down Timer Circuit Diagram
When the voltage across the capacitor reaches +8.1V, Q1 turns on via ZD1 and so Q2 turns off and switches off the relay - ie, this gives the "up" timeout. Using the values shown for C1, R2 and ZD1 gives an "up" duration of approximately 6 seconds - long enough to fully extend the antenna. D1 discharges C1 (via resistor R1) when the +12V supply is later removed.
When the radio is switched off (or a CD placed into the stereo unit), the radio antenna control output switches back to 0V. This does several things: first, it turns Q4 off and this allows Q3 to turn on due to the stored charge in C2. Q3 and RLYB now turn on for about six seconds - ie, while C2 discharges via R4 - and this switches power to the motor in the opposite direction to drive the antenna down. Diodes D4 and D5 are there to prevent C2 from discharging back via the circuitry around on Q1 and Q2.
Author: Peter Howarth - Copyright: Silicon Chip ElectronicsSunday, March 31, 2013
How to Make a Telephone Amplifier Circuit
The simple telephone ring tone amplifier circuit explained in this article saves the inconvenience of picking the telephone handset while speaking over a call. This circuit also particularly becomes useful when theres a need of the conversation to become audible to a number of people or a group of people.
When the conversation needs to become public the amplifier circuit simply needs to be switched ON so that rhe on going talks becomes amplified and can be heard loud and clear.
The most impressive feature of the proposed circuit design is that it does not require a direct or physical integration with the telephone line rather everything is done quite wirelessly.
The sensing of the telephone signals is done by the pick-up coil which may be placed very close to the telephone or the telephone wire.
The telephone pickup coil is made up of about 2000 to 3000 turns of 36 SWG super enameled copper wire wound over a plastic/paper former having a diameter of 2 inches.
Since this coil becomes the sole sensing agent should be made with lot of care and concentration.
Refer circuit diagram
When placed near to the telephone wire, the signals from the wire are transferred to the coil through the principle of mutual conduction and the audio pulses which is created by talking over the telephone mic is picked by the coil and sent to the main circuit for amplification.
The amplifier unit basically consists of the IC CA 3020 which forms the heart of the circuit. It just requires a few other passive components for the IC to become fully operational as en efficient audio amplifier.
The sensed input from the coil is not more than 300 mV, but becomes quite sufficient for the IC CA3020 to process the input into an amplified version over the connected loudspeaker.
Adjustments
After you finish assembling the circuit as shown in the figure, connect the pick up coil wire across the input of the amplifier and ground via the shown pot. Use shielded wire for this otherwise many unnecessary stray inputs may get into the amplifier. The pot acts as the sensitivity control or the volume control here.
Now switch on the power to the circuit.
Next gently place the pick up coil near the wire of the handset of the landline receiver.
Now as you lift the handset, the dial tone from the telephone should be heard loud and clear over the amplifier loudspeakers.
Make a call over the phone through another phone, all the audio during the calling procedure will be picked by the telephone amplifier circuit and converted into audible signals.
You may either use a battery for operating the circuit or a simple regulated power supply may be used. Alternatively you may use an AC DC adapter also for powering this circuit.
When the conversation needs to become public the amplifier circuit simply needs to be switched ON so that rhe on going talks becomes amplified and can be heard loud and clear.
The most impressive feature of the proposed circuit design is that it does not require a direct or physical integration with the telephone line rather everything is done quite wirelessly.
The sensing of the telephone signals is done by the pick-up coil which may be placed very close to the telephone or the telephone wire.
The telephone pickup coil is made up of about 2000 to 3000 turns of 36 SWG super enameled copper wire wound over a plastic/paper former having a diameter of 2 inches.
Since this coil becomes the sole sensing agent should be made with lot of care and concentration.
Refer circuit diagram
When placed near to the telephone wire, the signals from the wire are transferred to the coil through the principle of mutual conduction and the audio pulses which is created by talking over the telephone mic is picked by the coil and sent to the main circuit for amplification.
The amplifier unit basically consists of the IC CA 3020 which forms the heart of the circuit. It just requires a few other passive components for the IC to become fully operational as en efficient audio amplifier.
The sensed input from the coil is not more than 300 mV, but becomes quite sufficient for the IC CA3020 to process the input into an amplified version over the connected loudspeaker.
Adjustments
After you finish assembling the circuit as shown in the figure, connect the pick up coil wire across the input of the amplifier and ground via the shown pot. Use shielded wire for this otherwise many unnecessary stray inputs may get into the amplifier. The pot acts as the sensitivity control or the volume control here.
Now switch on the power to the circuit.
Next gently place the pick up coil near the wire of the handset of the landline receiver.
Now as you lift the handset, the dial tone from the telephone should be heard loud and clear over the amplifier loudspeakers.
Make a call over the phone through another phone, all the audio during the calling procedure will be picked by the telephone amplifier circuit and converted into audible signals.
You may either use a battery for operating the circuit or a simple regulated power supply may be used. Alternatively you may use an AC DC adapter also for powering this circuit.
Friday, March 29, 2013
5 A Constant Voltage Constant Current Regulator Circuit
This is a design circuit for constant voltage constant current (CVCS) regulator doesn’t mean a system with a constant load, since there will be no regulation in such case. What we call CVCS regulator is a regulator with two modes. This is the figure of the circuit;
The first mode is constant voltage, where the regulator trying to regulate the supply to a variable load at a constant voltage. In this mode off course the current will be variable depending on the load. The current will vary a range that is limited to a predetermined maximum current level. When the load draw more current than this level then the regulator will switch to constant current mode, where the regulator keep the current at a fixed maximum value. Any attempt of the load to draw more current will cause the regulator to decrease the voltage as a reaction to keep it constant, so it acts like a current limiter. Here is the schematic diagram of the CVCS regulator.
R tC Servo Tester Circuit
Here’ s a design circuit for servo signal is a simple digital pulse. It spends most of its time at a logic low (0 V). About every 20mS it goes logic high (3 to 6 VDC) and then quickly goes low again. It is this tiny window of logic high time, called the pulse width, that gets the attention of the servo. Here’s the figure of the circuit;
Please refer to the drawing. The period labeled "A" is called the frame rate. In the example it is repeated every 20mS (50 times per second), which is quite typical for most radio systems.Modern servos define center as a 1.5mS pulse width, as shown by detail "B" in the drawing. Full servo rotation to one side would require that this pulse width be reduced to 1.0mS. Full rotation to the other side would require the pulse width to increase to 2.0mS. Any pulse width value between 1.0mS and 2.0mS creates a proportional servo wheel position within the two extremes. The frame rate does not need to change and is usually kept constant.
The servo will not move to its final destination with just one pulse. The servo amp designers had brilliantly considered that multiple pulses should be used to complete the journey. This little trick reduces servo motor current draw and it helps minimize erratic behavior when an occasional corrupt signal is received. To move the servo, you must repeat the pulse every few milliseconds, at the chosen frame rate. Modern R/C systems use a 40Hz - 60Hz frame rate, but the exact timing is not critical. If your frame rate is too slow, your servos movement will become rough. If the rate is too fast the servo may become very confused.
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