Questions tagged [detector]

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Peak/envelope detector circuit for 30 MHz sine pulses with a 10 kHz PRF

My goal is to input 30MHz sine pulses, with a pulse width of 10us and gap of 90us between the pulses. The circuit should convert this pulse train to a TTL signal that goes from 0 to 5 volts. To ...
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Is this circuit measuring the electrical field?

I have found the following circuit on the web (https://electroclinica.org/2018/03/23/fabricacion-de-un-sencillo-medidor-de-campo-de-rf-diy/) which claims to be an "RF field" detector/meter/...
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How to add more lights and sirens to motion detector

I have a motion detector size of a cigarette box that rings bell or simple song when activated using a small remote control. We turn it on after closing the business to go home. We've had many ...
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2 answers
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HF Peak detector

This is a peak detector taken from page 21 of the opamp ADA4610: I need it to capture peaks from 500KHz sine wave. I can't understand why when the sine starts it goes above the peak and then ...
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1 answer
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Novice looking for help with a current sensor circuit

I'm an electronics novice trying to figure out how to detect when current is flowing to certain tools in my shop so I can add some automation to my dust collection system. I essentially want to build ...
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-1 votes
2 answers
115 views

Gain of photodetectors

I found this in a lecture about "Optical Wireless Communications." It is slide 15. Does anyone have idea how gain was computed?
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2 answers
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Antenna for contactless 50/60Hz AC detector

Many simple circuits can be found online for building an AC detector that look something like the circuit below. These are simple devices to e.g detect AC lines in your walls. They feature a short ...
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APD Module and A/D card

I want to make a LDV/PDPA device for measuring the diameters of droplets. For this device I need to use APD photodiode to gather the scattered light from droplets. I searched for PADs and found a ...
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3 answers
280 views

Balance metal detector sensitivity for smaller pieces of metal

As suggested by Andy in these posts proximity sensor technology, range of 150mm, Metal detector "Head sensor" and How can I drive an LC tank circuit to get a nice and clean sine wave?, I ...
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2 answers
153 views

AC current detector / sensor without splitting wires

I saw this question about measuring AC current without splitting wires. I understand why this is difficult and inherently imprecise. Is it, however, easy to just detect whether an appliance is on or ...
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-1 votes
1 answer
153 views

Simulate a double balanced coil for a metal detector on PROTEUS

I am trying to build a metal detector with double balanced coil, (the scheme source is the french magazine : L'ELECTRONIC POUR TOUS project: EN1465 Un détecteur de métaux très sensible, the magazine ...
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10 votes
6 answers
952 views

A few questions on PIRs and other motion detectors

I grew up incorrectly believing that motion detectors (as part of burglar alarm systems) were designed to detect movement, when in actual fact it is the movement of a heated (like body heat) object ...
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1 answer
280 views

Circuit to detect only one zero crossing when a sine wave changes from negative to positive half cycle

In a Grid Tie Inverter design, I need a circuit which can detect only one zero crossing of the Grid signal, (when the signal will change from negative to positive half cycle). I have made a circuit, ...
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1 vote
1 answer
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Detecting a location of the needle inside a cavity having multiple IR emitters , using IR Detector at the tip of the needle

I am working on a project where I need to find the location of a needle that has the IR detector at the tip of the needle. These needles are medical suturing needles that would help us to detect the ...
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1 answer
66 views

Microwave detection circuit verification

I want to develop a circuit which can detect electromagnetic waves (radio wave, microwaves.) This circuit will just act as a tamper detect and not physically measure/compute the radiation. I have ...
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1 answer
189 views

Metal detector circuit description

I found a circuit for this metal detector and would like to make PCB. I can not find anything about this circuit. Maybe someone would know what this circuit is. What are the best component housings to ...
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2 answers
487 views

Why are alkalines "required" for metal detectors?

A handheld metal detector specifies only "Alkaline" batteries and not "heavy duty" or "rechargeable". Since there are li-ion 9v batteries available not at low cost I was ...
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1 answer
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Designing a Light/Dark Sensor with LDR 555 alternator LED and Motor

I am working on a project which I need to turn on LED alternately as well as motor turned on while it is dark. I managed to create an Electric circuit which can turn on the LEDs together. However ...
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Feed-through termination to vary bandwidth and signal power

I'm currently facing an interesting problem regarding RC low-pass filters. In my experimental setup, I have a reverse-biased photodetector (DET01CFC from Thorlabs). To amplify this signal, I make use ...
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1 answer
106 views

Is this a demodulated signal?

1st attempt I have a problem. I built the FM demodulator circuit, but i am not sure if this signal is demodulated. This was my first attempt which following an answer, resulted in a 2nd attempt ...
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1 vote
1 answer
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How to balance antiphase Rx coil in metal detector?

In this question How can I drive an LC tank circuit to get a nice and clean sine wave? I learned to get clean oscillation waves of a tank circuit (Tx) and consequently its reception through antiphase ...
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2 votes
3 answers
492 views

How can I drive an LC tank circuit to get a nice and clean sine wave?

As advised by Andy in this post, I constructed single loop transmit and receive coils: I use this circuit to transmit a powerful field: The Tx signal has a large spike that is reflected in the Rx ...
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1 answer
119 views

Linear regulator power consumption

I have this circuit linear regulator with UVLO so I would like to calculate the power consumption of this block any person can help me, please Vout = 1.5 V (Iss = 15.2 μA, Vout = 1.5 V, switching = 32....
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1 vote
1 answer
467 views

Envelope detector RC values [closed]

I have understood how the envelope detector works, but I am unable to find the formula for R and C appropriate values. The closest I have found is this link: Explain The Square Law Demodulation and ...
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0 answers
28 views

Maximizing signal to noise ratio for very small radiation detector

I have a very small radiation detector that outputs signal of small amplitude. Requires preamplification before going to an actual amplifier. When constructing the system prior to the preamp, would I ...
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1 answer
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How do I calculate the power consumption of the polarity detector circuit?

What method can I use to calculate the power consumption of this block? In the paper it's equal to 3 μW at 1.5 V. The datasheet of the piezo sensor. The datasheet of the MAX9119 comparator. Circuit:
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1 answer
160 views

How does this under voltage lockout (UVLO) work?

In my project, I need an under voltage lockout (UVLO) to connect the load electronics to the energy-storage element via a power-gating transistor when the voltage across the supercapacitor exceeds ...
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2 votes
1 answer
520 views

Help choosing modern replacement for Hitachi 1SS86 Schottky diode

I’m trying to find a modern Schottky diode to use instead of the 1SS86 Schottky diode (Hitachi version, specifically). I want to use it along with a low current LED to build a lectenna that works for ...
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0 votes
0 answers
54 views

Fisher Scientific T-30 Metal Detector - Circuit schematic

Looking for service manual for this old thing or a very similar detector it is from 1965 with germanium transistors .. I didn't think there was any real use for it until someone asked .. some photos ...
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1 vote
2 answers
156 views

Infant cry detector

I want to use an electret microphone to detect infant cry. I came up with this design: According to those papers: Pitch Analysis of Infant Crying Frequential Characterization of Healthy and ...
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1 vote
1 answer
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Amplitude detection

Why is second analog multiplier(marked with red color) used to detect the amplitude of the input signal in this circuit instead of diode? The point of this circuit is to maintain the output level of ...
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1 vote
1 answer
189 views

Simulation of voltage sensitivity of ideal detector diode circuit

Application note 969 derives the voltage sensitivity at zero bias of a detector diode: \$ \gamma = \frac{V_o}{P_{\rm in}} = \frac{0.52}{I_s(1+\omega^2 C_{j0}^2 R_S R_V)} \cdot \frac{R_L}{R_V+R_L}, \$ ...
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2 answers
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Switch off power when 0v is sensed / Short to ground

I have already posted this question but I made a mess of the diagram so deleted it and am posting again, apologies to anyone to answered the original question. I'm fairly new to electronics and am ...
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2 answers
274 views

How would i go about detecting if a rs-485 cable is plugged in?

The basic problem were trying to solve is certain secondary device's cables gets left unplugged and we need a way to detect a cable that is plugged into my device,and check if that cable is actually ...
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0 votes
0 answers
59 views

Transformer-insulated flame ionization detector. How to improve response? Triode, messure current safety, ignition fires

I am trying to do a isolate flame ionization detector with a transformer ignition. But, when I put it on the frame, nothing change.. (0.2VAC) I put a amplifier (10 teraohms impedance) to read the ...
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3 votes
2 answers
99 views

Use of ceramic capacitors in HV system

When I opened the supply board to the detector (Geiger counter,) I got the above circuit. The detector uses a gas-filled tube with a central wire at high voltage to collect the ionization (charge) ...
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0 votes
2 answers
106 views

Sequence Detector forced to wait a specific number of bits

So I have this little problem, where I am supposed to build a sequence detector which is forced to wait a specific number of bits before going into the reset state. It's kind of like pin codes work. ...
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1 vote
3 answers
753 views

Most simple way to detect small voltage changes(~150mV)

I have one unit of museum cabinet detector that works on 18v. I want make simple security circuit with detector. I've figured out that two output ports on detector are normally contact(NC), but it'll ...
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2 answers
407 views

Defect LED detection for car lights

The schematic beneath is a new project of me. The theory behind this is: My car has a very fool proof bulb failure detection and warning system. CANbus proof LED bulbs can't fool the car and just a ...
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3 votes
1 answer
77 views

Noise in crystal detectors (historical)

I'm reading over the history of British WWII radar systems, and one thing that really struck me was the improvement in crystal detectors. The were a vital component of microwave radars, and while the ...
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0 votes
2 answers
738 views

How inductance of a coil changes when there is a metal object nearby?

I am not sure if it is increasing or decreasing as some sources say it is increasing whereas some say it is not. What actually happens when a metallic object is put under a coil that is meant to be ...
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1 answer
136 views

NC Opening Contact detector to drive a NO relay Contact circuit

I'm looking for a simple +5.5vdc powered circuit (perhaps a PNP transistor driving a NO Reed Relay coil?) - I need a circuit that can detect when a pair of Normally Closed contacts with no voltage ...
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1 answer
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Motion Detector Time Adjustment

What it means when adjustment area is: 10±5 s-10min? I cannot find a solution from Google.
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1 vote
2 answers
134 views

Automotive tachometer signal interpretation

I'm trying to build a custom dashboard for a car (Daewoo Lanos 1998 with Delco ECU). Tachometer signal, that comes to dashboard with a separate wire looks a bit strange to me. It seems that the signal ...
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0 answers
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Choosing a suitable PFD for PLL

I'm building a capacitive vibration sensor and it has to reject the stray capacitance by locking the LC oscillator at 64 MHz, where I can demodulate relatively small frequency changes. The best way to ...
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0 votes
1 answer
727 views

LTSpice - envelope detector LPF behaving like buffer

I have an issue with an LTSpice simulation and I'm not sure if the issue lies in the simulation setup or somewhere more basic. The simulation is as follows: The system is as follows: on the left, ...
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-4 votes
1 answer
80 views

do is anyway to detect Tablets Pills package is empty or not? [closed]

do infrared sensor can pass through transparent plastic and work?
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0 answers
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Understanding the basics of AC coupling

The real case I am working on: I need to connect a CZT (Cadmium-Zinc-Tellurium) detector to a custom ASIC input (a Charge Sensitive Amplifier of which I do not know the input impedance, if that ...
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1 answer
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Missing pulse detector for low input?

I'm looking to implement a watchdog circuit. Tried the standard "missing pulse detector" schematic such as one from http://www.falstad.com/circuit/e-555missing.html - and it works well when the input ...
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Can you convert a headphone into a metal detector coil?

I was wondering if it's possible to convert a stereo headphone into a coil to be used as a signal transmitter and receiver for metal detecting? The idea is to use a smartphone as a signal generator.
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