Showing posts with label generator. Show all posts
Showing posts with label generator. Show all posts
Wednesday, November 12, 2014
PWM Discrete Generator Circuit and explanation
PWM waveforms are commonly used to control the speed of DC motors. The mark/space ratio of the digital wave-form can be defined either by using an adjustable analogue voltage level (in the case of a NE555 based PWM generator) or digitally using binary values. Digitally derived PWM waveforms are most often produced by the timer/counter modules in microcontrollers but if you do not want to include a microcontroller in your circuit it’s also quite simple to generate the signals using discrete logic components.Circuit diagram:
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Discrete PWM Generator Circuit Diagram
An extension of the circuit shown can produce two PWM wave-forms from an 8-bit digital input word. Each signal has 15 values. The 8-bit word can be produced for example from an expansion board fitted in a PC or from an 8-bit port of a processor which does not have built-in PWM capability or from a laptop’s printer port. The mark/space ratio is only programmable up to 15/16 rather than 16/16; a binary input of 0000 produces a continuous low on both outputs turning both motors off.
Similar circuits often employ a dedicated ‘enable’ input to turn the motors off but it is not necessary in this design. The diagram shows the circuitry required to produce just one waveform. For the full two channel circuit it is necessary to use an additional 74HC193. The clock signal produced by the HCF4060 generator can be used to drive both channels and the free flip flop in the 74HC74 package can be used for the second channel (the corresponding pin numbers are shown in brackets). Altogether the entire two channel circuit can be built using just four ICs.
Discrete PWM Generator Circuit Diagram
An extension of the circuit shown can produce two PWM wave-forms from an 8-bit digital input word. Each signal has 15 values. The 8-bit word can be produced for example from an expansion board fitted in a PC or from an 8-bit port of a processor which does not have built-in PWM capability or from a laptop’s printer port. The mark/space ratio is only programmable up to 15/16 rather than 16/16; a binary input of 0000 produces a continuous low on both outputs turning both motors off.
Similar circuits often employ a dedicated ‘enable’ input to turn the motors off but it is not necessary in this design. The diagram shows the circuitry required to produce just one waveform. For the full two channel circuit it is necessary to use an additional 74HC193. The clock signal produced by the HCF4060 generator can be used to drive both channels and the free flip flop in the 74HC74 package can be used for the second channel (the corresponding pin numbers are shown in brackets). Altogether the entire two channel circuit can be built using just four ICs.
Friday, November 7, 2014
Tri Waveform Generator
The Tri-Waveform Generator can be used for a number of different uses. The one that I use it for is a signal generator to test circuits. The frequency range is 20 to 20khz. and can be adjusted by R1. The duty cycle or the time that the waveform is high and the time that the waveform is low can be adjusted by R4. The purpose of R2 and R3 are to clean up any distortion on the sine wave output. To do this you must hook up the sine wave output to and oscilloscope and adjust R2 & R3 to make the sine wave as accurate as possible.
Wednesday, November 5, 2014
Triangular Wave Generator Circuit
Triangular Wave Generator Circuit
As a reset circuit, the generator embodies an integrator as a ramp generator and a threshold detector with hysteresis. There is no further explanation is needed because the integrator has been described in a previous section. It’s a latch circuit with a large dead zone, on that case, the threshold amplifier detector is similar to a Schmidt Trigger. By using positive feedback around an operational amplifier, we can implement this function. The positive feedback network provides a voltage at the non-inverting input which is determined by the attenuation of the feedback loop and the saturation voltage amplifier when the amplifier output is in either the positive or negative saturated state. The voltage at the input of the amplifier must be caused to change polarity by an amount in excess of the amplifier input offset voltage to cause the amplifier to change states. When this is done, until the voltage at its input again reverse, the amplifier saturates in the opposite direction and remains in that state. By examining the operation with the output of the threshold detector in the positive state, the complete circuit operation may be understood. To cause a current I+ to flow, we have to apply the detector positive saturation voltage to the integrator summing junction through the combination R3 and R4.Then, a negative-going ramp with a rate of I+/C1 volts per second until its output equals the negative trip point of the threshold detector is generated by the integrator. After that, at the integrator summing point , the threshold detector changes to the negative output state and supplies a negative current, I-. A positive-going ramp with a rate of I-/C1 volts per second is generated by the integrator until its output equals the positive trip point of the threshold detector where the detector again changes output state and the cycle repeats. R3, R4, C1, and the positive and negative saturation voltages of the amplifier A1 determine the triangular-wave frequency. Amplitude is determined by the threshold detector saturation voltages and the ratio of R5 to the combination of R1 and R2. If the detector has equal positive and negative saturation voltages, positive and negative ramp rates are equal and positive and negative peaks are equal. If the inverting input of the threshold detector, A1, is offset with respect to ground, the output waveform may be offset with respect to ground. If the detector is clamped with matched Zener diodes as shown in following figure, the generator may be made independent of temperature and supply voltage. If power supply impedance causes oscillation during its transition time, the detector may be compensated and the integrator should be compensated for unity-gain. For maximum symmetry, the current into the integrator should be large with respect to Ibias and offset voltage should be small with respect to Voutpeak.
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This is a circuit for a constant amplitude triangular-wave generator. A variable frequency triangular wave whose amplitude is independent of frequency is provided by this circuit. This circuit is based on LM101.
Triangular Wave Generator Circuit
As a reset circuit, the generator embodies an integrator as a ramp generator and a threshold detector with hysteresis. There is no further explanation is needed because the integrator has been described in a previous section. It’s a latch circuit with a large dead zone, on that case, the threshold amplifier detector is similar to a Schmidt Trigger. By using positive feedback around an operational amplifier, we can implement this function. The positive feedback network provides a voltage at the non-inverting input which is determined by the attenuation of the feedback loop and the saturation voltage amplifier when the amplifier output is in either the positive or negative saturated state. The voltage at the input of the amplifier must be caused to change polarity by an amount in excess of the amplifier input offset voltage to cause the amplifier to change states. When this is done, until the voltage at its input again reverse, the amplifier saturates in the opposite direction and remains in that state. By examining the operation with the output of the threshold detector in the positive state, the complete circuit operation may be understood. To cause a current I+ to flow, we have to apply the detector positive saturation voltage to the integrator summing junction through the combination R3 and R4.Tuesday, November 4, 2014
Long Interval Pulse Generator
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 :
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.
Saturday, October 25, 2014
IC TLC271 Single supply Function Generator
The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistor R4 and R5. The output is fed back to the non-inverting input of the first stage to control the frequency.
The amplitude of the square wave is the output swing of the first stage, which is 8V peak-to-peak. The second stage is basically an op amp integrator.
Tuesday, August 12, 2014
Tri Waveform Generator Wiring diagram Schematic
The Tri-Waveform Generator can be used for a number of different uses. The one that I use it for is a signal generator to test diagram. The frequency range is 20 to 20khz. and can be adjusted by R1. The duty cycle or the time that the waveform is high and the time that the waveform is low can be adjusted by R4. The purpose of R2 and R3 are to clean up any distortion on the sine wave output. To do this you must hook up the sine wave output to and oscilloscope and adjust R2 & R3 to make the sine wave as accurate as possible.
Source by : Streampowers
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