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Electrical Engineering

Questions tagged [schmitt-trigger]

Anything related to Schmitt trigger circuits. Schmitt triggers are positive feedback comparator circuits exhibiting hysteresis.

142 questions
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Voltage appears on comparator input

I have made a pcb . A part of the circuit is the Schmitt trigger comparator seen above . The positive feedback resistors are chosen to give the noniverting input values from zero to 0.5 volts . ...
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57 views

Flashing an LED with Schmitt trigger

I'm trying to build the above circuit, which is supposed to flash an LED with a schmitt trigger (with the possibility to vary the frequency with the knob of the 47kOhm potentiometer). I don't have a ...
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88 views

Schmitt Trigger: Problems between theory and reality

I want to say that I am not a native English speaker so you may find some writing errors. Also, I am just learning electronics, so sorry if some questions are poorly formulated. I am trying to build ...
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51 views

Schmitt trigger oscillators interfere with eachother (74HC14)

I am using a single 74HC14 (hex schmitt trigger) to implement three oscillators. I now have a test build ready and encounter problems. See schematic, it shows component values. Also proper 5V power ...
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94 views

Need help understanding an electronic oscillator (Schmitt trigger + capacitor) [duplicate]

When we use this circuit, the LED blinks. I know an inverter transforms high to low voltage and low to high voltage, but here the voltage source is connected to the inverter all the time so the ...
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31 views

Simplest schmitt trigger with fewest part count for microcontroller

I own several AT89C4051 microcontrollers and I'm currently trying to read signature bytes of the micros that I probably broke (by applying 7.2V to the VCC pin before noticing the 5V regulator became a ...
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22 views

Lowest resistor value for enclosed light sensor unit with nearby lighting without losing sensitivity

This is a drawing I made of a light sensor unit I'm creating. Inside of it, I have a circuit board containing 3 7-segment displays and I have two photo-transistors (yellow half-circles in the picture) ...
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1answer
436 views

Why is this BJT Schmitt trigger producing a sine wave?

I am trying to build a Schmitt trigger from a pair of BJTs to convert a sine to a square wave. The sine wave is from a Colpitts oscillator running at over 150 MHz. I want to measure the ...
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38 views

Determining U_ref on Schmitt Trigger

If I have only starting values a U_high=3V and U_low=2V (pulse signal on V3 on schematics), can I determine a U reference, that's given us on the inverting input of the op. amp.? My calculations were:...
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1answer
79 views

Op. amp. with integrator - enough values to start?

All the red-circled values (Uref, C2, R31 and R36) are missing. I'm supposed to calculate them, but I think there's at least one value missing. Shouldn't Uref be known to calculate the rest of the ...
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217 views

Schmitt Trigger not reaching full saturation

I'm trying to develop a sensor based on the optoelectronic device CNY70. I want to filter the signal in order to be read by a microprocessor, where the threshold to change between logic levels could ...
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65 views

Need help to increase schmitt trigger sensivity in a circuit

I need help on a circuit I've designed to detect hits on a piezo sensor on a drum. It uses an opamp with 2 channel, on goes to a schmitt trigger, the other to the ADC input on the XMEGA ...
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44 views

Schmitt trigger inverters or regular inverters for clean high speed data processing

I made a circuit in which data is passed in from phototransistors (part# PT334-6C) into a microcontroller (part# AT89C4051) serial port via schmitt trigger inverters (part# 74HC14) and a demultiplexer ...
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1answer
157 views

Schmitt trigger with 741 op-amp not behaving as in simulation

I am implementing a Schmitt trigger using the circuit shown below. This circuit consists of one LM741 op-amp, which acts as an asymmetrical Schmitt trigger with a single power supply. According to ...
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1answer
93 views

cd40106 Problems

so im trying to make this simple oscillator using ic cd40106 without any succsess. it's the usual astable multivibrator configuration using a 9v pwr supply, 220k resistor and a 2.2uf capacitor, the ...
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154 views

Why do I get a triangle wave in this Schmitt trigger oscillator?

I'm trying to design a function generator that can generate square, triangle and sine waves, with frequency varying between 100Hz and 100kHz. The circuit in the blue box is supposed to be a schmitt ...
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2answers
301 views

Flip a Schmitt-Trigger when current flows through a Zener diode

I am trying to design a circuit using an intermitent power source (a bicycle hub generator), which is rectified and filtered, and regulated at 6,8V. Now I want to "detect" when the power source is ON ...
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49 views

Schmitt trigger versus Hysterisis Comparator

I'm working to create an ultrasonic sensor to be used in object recognition. I've been studying various schematics and current sensors on the market - the most common being the HC-SR04. When viewing ...
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1answer
737 views

How does a “speed up capacitor” work in Schmitt trigger?

Hello I'm trying to understand how adding a capacitor across R2 in below circuit increases the switching speed. I don't see how C2 supplies charge to C1. With the additional capacitor C2, it seems ...
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62 views

Analytically obtaining the hysteresis of an opamp Schmitt trigger with RC network in its inverting input

This is a follow-up from here. I have got the following Schmitt trigger circuit implemented already on a breadboard. As seen, the input signal at the non-inverting and inverting terminals of the op ...
0
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1answer
49 views

Strange state in input at the amplifier

I have this schematic, an invert Schmitt trigger attached to the RC component to create a triangle wave. It's an oscillator. The two oscillators go in to the amplifier, but I don't understand why I ...
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1answer
101 views

Comparing two variable voltages with hysteresis

All of the designs I have seen for adding hysteresis to a comparator (Schmitt triggers) assume that one of the two inputs to the comparator is set at a fixed reference voltage (typically with a ...
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1answer
119 views

Are Schmitt trigger and peak detector comparator the same?

Here is a peak detector comparator schematic ,its symbol,and its simulation.I have some question about them. First,we all know the Schmitt trigger symbol is the same as the second picture,so are ...
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3answers
207 views

Calculating R and C for schmitt trigger debouncer

I've been looking all over the internet to try to figure out the optimal values for R1, R2, and C but couldn't find info. I'm trying to ideally make a debouncer that will work with any button on the ...
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1k views

Can multiple Schmitt triggers in series fully debounce a switch?

After dealing with software debouncing for a while, I find it takes a huge toll on the system, so I thought of initially making a hardware debouncer with one Schmitt trigger (74HC14), a capacitor, ...
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1answer
44 views

Schmitt trigger issues… lumpy outputs and wrong switching voltages

I'm trying to implement the Schmitt trigger found in "CMOS" by J. Baker. Here's what the circuit should look like: And this is how the transistors should be dimensioned to achieve switching voltages ...
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1answer
312 views

Inverting schmitt trigger with pnp transistors

I have a question regarding Schmitt Trigger. I am trying to design an inverting output (at UTP=Low, at LTP=High) Schmitt Trigger for an application. However, I need to use PNP transistors since the ...
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183 views

Schmitt trigger with three transistors

I usually understand well transistors circuits, but I just can't get to work with this one: (Note the circuit is powered with +/- 12V) It is supposed to be a schmitt trigger circuit, and I'm trying ...
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3answers
1k views

Schmitt trigger - why is there no current over the second transistor?

I'm reading through The Art of Electronics, and I'm trying to wrap my head around a Schmitt trigger. simulate this circuit – Schematic created using CircuitLab Why is there no current over Q2 ...
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5answers
2k views

Hardware debouncing of key matrix with minimum passive components

I have recently bought this cheap 4x4 keypad matrix. It only has the push-buttons and nothing else therefore I want to add a proper debouncing to it. The debouncing in software is something I want to ...
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1answer
271 views

Calculate transfer function H(w) of Schmitt trigger with RC at inverting input

I have got the following Schmitt trigger circuit implemented already on a breadboard. As seen, the input signal at the non-inverting and inverting terminals of the op amp is the same, but with the ...
3
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3answers
673 views

How to determine the saturation level when an opamp schmitt trigger starts worknig?

The Opamp inverting schmitt trigger is constructed as shown. The output signal is So I ask why is the output at the start of operation saturated to positive? Also, if the input voltage is moved ...
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111 views

Design Schmitt Trigger

Use Schmitt trigger to design a 1 kHz square wave oscillator. Assume the Op Amp supply voltages to be +15V, and the maximum bias current of the Op Amp to be 500nA. Assume that the maximum output of ...
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1answer
129 views

ADC preamp using Schmitt trigger, opamps and transistor reset

I would like to validate this design I use for input to a microcontroller for a piezo microphone trigger. I use 3 lines: a Schmitt trigger for use with an interrupt, an analog line for measuring the ...
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1answer
301 views

Sine to square wave high frequency [closed]

I have a school project that requires a sine to square wave converter for a sine wave input of 0 - 3.1 V pk from 0Hz to 500kHz. The output must be a square wave with maximum voltage 2.8V - 3.1V. So ...
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2answers
2k views

Schmitt trigger in button debouncer

While researching how to debounce a switch for digital applications, I often come around this diagram : simulate this circuit – Schematic created using CircuitLab Or other similar diagrams, ...
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1answer
149 views

Schmitt Trigger configuration for enabling power from guitar pickup

I would like to enable power to a regulator from a 1Vpp guitar pickup. Threshold can be between 0.2V and 1V. And I need it to disable after about 60 seconds of no signal from the pickups. I'm ...
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5answers
1k views

Why do TTL pulse generators generate an asymmetrical square wave (unlike CMOS)?

I've read that the asymmetrical (about 1/3 mark-to-space) output waveform is due to input gate characteristics of a TTL inverter, but I want to know more about which characteristics of the TTL input ...
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2answers
113 views

Analog buffer/voltage follower with function table?

I'm looking for a buffer as I am going to fan out a VCM signal from an ADC to multiple ADC drivers. ADC VCM out: 0.95V 10mA ADC dr in : 10Kohm x 3 ...
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90 views

Schematic review for simple LED circuit?

I'm pretty new to circuit design, I am trying to make a small board with a few LEDS that uses a toggle to turn on and another toggle to either show the LEDS always on or to blink the LEDS. I believe ...
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2answers
169 views

RC integral and differential functions, Schmitt triggers. How does this circuit work?

I'd be happy if someone explained me why this circuit is the way it is; how does it work ? Also i would like to know what the value for C1 is. Taken from https://www.electroninvest.com/shop/items/...
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36 views

Parameter tolerance estimation with non-pure ratios

I am trying to estimate the exact tolerance of a simple circuit, consisting of an op-amp based, inverting comparator with hysteresis. This is the schematic (electronic-tutorials.ws) For which I ...
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2answers
458 views

Why doesn't this schmitt PWM circuit work as expected?

I've designed and built an adjustable PWM generator using schmitt trigger inverters. However, it doesn't seem to be working. Here is the circuit: The capacitors at the bottom are intended to be ...
0
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1answer
204 views

Schmitt Trigger for logic level conversion voltages up to +-20V

I want to be able to safely convert any voltages above a threshold voltage of +-1V with a maximum voltage level of +-20V to the logic level (3.3V). I ended up using an op-amp to construct a Schmitt ...
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1answer
856 views

Encoders debouncing with 7414 at 3.3V

I'm trying to make a small module that has 2 rotary encoders (both have build-in push buttons), hardware debouncing circuit and have to be compatible with both 5.0V and 3.3V microcontroller logic ...
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3answers
822 views

Schmitt trigger resistance

I was thrown off by a certain website while learning about a op amp Schmitt trigger design. The layout was the same inverting config as the above schematic but gave a confusing answer to calculating ...
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1answer
108 views

Circuit or Equipment to delay high speed square clock signal?

Hi I have a ttl clock signal that id like to change the phase of to see if it changes effects the unit under test (not relevant but its a digital transmitter and an automated testing setup) this way I ...
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1answer
422 views

CMOS Schmitt Trigger: contradictionary information

Weste and Harris in "CMOS VLSI Design" describe the CMOS trigger as follows: Let's call the transistors in the first columns from bottom to top M1,M2; M4,M6 and the transistors in the second column ...
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1answer
163 views

Comparison between the performance parameters of Tristate buffer and Schmitt Trigger

I want to know the comparison between the performance parameters of Tristate buffer and Schmitt Trigger. By performance parameters, I mean things like propagation delay,power consumption etc. Thank ...
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1answer
110 views

Help needed trying to build an audio sawtooth oscillator

I'm a total beginner hobbyist trying to understand the concept of an audio synthesizer, with a view to building one. Rather than just build a kit I'm keen to understand the concepts. Goal: build a ...

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