Questions tagged [detector]

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votes
1answer
52 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 ...
0
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0answers
40 views

How to calculate the ripple voltage of the output in the attached circuit?

In the attached drawing, I know the discharge constant time is RC=2ms, which is very close to the input signal cycle time T=1/400=2.5ms. I am trying to derive the ripple voltage through the attached ...
0
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2answers
54 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 ...
0
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1answer
49 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 ...
0
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1answer
29 views

Motion Detector Time Adjustment

What it means when adjustment area is: 10±5 s-10min? I cannot find a solution from Google.
1
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1answer
70 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 ...
0
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0answers
80 views

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 ...
0
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1answer
74 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, ...
-4
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1answer
68 views

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

do infrared sensor can pass through transparent plastic and work?
0
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0answers
59 views

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 ...
0
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1answer
59 views

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 ...
0
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1answer
40 views

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.
1
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2answers
115 views

Comparator as a current detector

I'm looking for a simple circuit that uses only a comparator (or an opamp) to detect the presence of a small current through a high-side current resistor. The idea is for a microcontroller input to go ...
4
votes
2answers
90 views

Reducing the range of a D flip-flop frequency detector

I'm designing a frequency tracking circuit and I came up with a circuit that tracks frequencies from Fclk to Fclk/2: However, it would be very nice if the bandwidth was a bit narrower, from Fclk to ...
2
votes
2answers
110 views

Is it possible to convert the audio signal from a smartphone's headphone jack into radiowaves? [closed]

I was watching a video of someone using his smartphone and a custom designed coil to make a metal detector. The smartphone was connected to the coil via headphone jack. I couldn't understand how he ...
0
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0answers
152 views

Reading analog signal of metal detector using arduino

I would like to tap into analog signal of Garrett AT MAX metal detector (ínfo) and read the value using arduino analog in. Schematics for the metal detector can be found here It seems to me that the ...
2
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2answers
531 views

Bandpass Filter: Single supply op amp design

I have taken on a hobby project and I am trying to make a circuit which would be able to identify an acoustic signal with a frequency of 40kHz. Here is the circuit of a band pass filter for this: ...
-1
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1answer
74 views

My mobile detector circuit won't work

I'm trying to get C3 to detect RF signals from a mobile phone. Amplify this signal to detect it using an LED. My main issue is simulating the antenna on multisim since multisim doesnt have an antenna!...
0
votes
1answer
85 views

Electronic detector to measure of distance? [closed]

I am not well known about electronic and it is my first question here, beforehand sorry for not qualified question. Let me try to explain what I am looking for: Is there chip or any another ...
2
votes
2answers
114 views

Is there a simple way to detect which connector is powered?

I have a circuit with two power connectors, J1 and J2. I would like to be able to detect which one the power is coming from. The trick is that the connectors need to provide power to each other. ...
1
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0answers
2k views

Metal Detector using IC 555 Timer project

I want to build some project about metal detector using integrated circuit 555 timer. I already made a schematic in proteus 8 application. I made some change with the original schematic i found on ...
1
vote
1answer
182 views

How to calculate noise power (dBm) of a photodiode?

I want to check the thermal noise spectrum of a photodiode (PD) at different frequency response but I do not know how to calculate it. Below graph is an example which shows noise power (dBm) as a ...
0
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2answers
414 views

Non contact (contactless) AC or DC detection?

I'd like to detect AC or DC current (not the current level just nothing or something => ON/OFF) in a wire with a (DIY) sensor just in contact (glued) with the wire plastic insulator. At the end the ...
-4
votes
3answers
229 views

How do I reverse-bias a resistor?

We all know that a photo diode can be used as a light detector and as a light emitter (although the way that it's built will usually make it specialized to prioritize one application over the other); ...
0
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0answers
71 views

Detecting ultrasonic by microphone and MCU

I design data-over-audio transmission to MCU. To do it i need ultrasonic detector with specific frequency, for example 50kHz. Seems, that electret microphone+low-pass filter+envelope detector will ...
1
vote
2answers
154 views

Flatness vs Frequency parameter in RF zero bias detectors

I require the measurement of RF power from a port, and I am considering using a zero-bias RF detector in order the measure the power being delivered through the port. These devices give a voltage ...
0
votes
1answer
141 views

What is the difference CMOS and CCD image sensors? In terms of Infrared spectrum [closed]

What is the difference between CMOS and CCD image sensor arrays? i.e working principles. Please consider in infrared spectrum. Which one's fabrication is expensive/ or cheap ? Which one gives ...
4
votes
5answers
941 views

Tri-State Detection

Some of you may have read my answer here to detect when two digital signals are either high or low, i.e. not both tri-state. One method uses window comparators the other opto-couplers to detect when ...
0
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0answers
621 views

Optical Smoke Detector design with Arduino: buzzer problem

I'm working on an Optical Smoke Detector using Arduino UNO board. Here is the circuit diagram: Whenever smoke is detected by the smoke sensor, the buzzer and LED should work. From the Arduino ...
0
votes
2answers
254 views

Envelope detector and DC voltage

I am currently working in the simulation of a physics project. One of the detectors inputs a voltage V1: V1(t)= D+Acos(wt) and tries to extract the amplitude. I read that a simple Envelope detector ...
0
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3answers
176 views

Peak detector circuit operation

So I understand that the capacitor charges up to the peak voltage and remains there since it cannot discharge due to the diode. But when I reduce the voltage on the input, the capacitor voltage also ...
5
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2answers
2k views

Why does this CO detector forbid the use of lithium batteries?

I have several Kidde KN-COB-LP2 CO detectors installed in my house. They look like this: They operate on standard AA-size alkaline batteries, and typically last several years on such batteries. The ...
-1
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2answers
350 views

Gap detector does not register high speed projectiles

I'm trying to build a gap detector-based ASG gun chrono. I successfully connected two gap detectors to Arduino Uno, wrote a program, which measures time between two voltage spikes (on each gap ...
2
votes
1answer
1k views

Light intensity and photodiode current

Recently i am using a LED as a photo detector . Follow by this instruction : http://makezine.com/projects/make-36-boards/how-to-use-leds-to-detect-light/ An opamp is used to convert the photocurrent ...
0
votes
1answer
515 views

detector in logic gate design

1.regarding to logic gate concept i have to design the circuit with 4 bits multiple of 3 detector. but when i trying to make logic gate and truth table it seems to me it's wrong so i have no idea ...
1
vote
1answer
395 views

Metal detecting using a small inductance

I have a coil with approximate indutance of 15uH used to detect metal through changes in inductance. I want to use an op amp or 555 to oscillate with frequency based on the inductance. However this ...
3
votes
5answers
706 views

Measuring relative rf signal strength [closed]

I'm trying to measure the relative signal strength received by a dipole antenna for orientation purposes. I'd like to do so using an ordinary multi-meter. I don't know much about RF circuits, but ...
2
votes
1answer
197 views

Building an inverted peak voltage detector

So I am trying to build a detector that will find the lowest voltage dip of a DC source. So for example, if I attach a load I can see what the voltage drops to. I have built this peak detector in ...
0
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0answers
62 views

Build a breathalyzer like device but for testing liquid or semi-liquid subtances

As a recovering alcoholic, I know for a scientific fact that alcohol will altogether evaporate from boiling water after sufficient time, and nearly all alcohol from boiling food, which would have a ...
1
vote
1answer
80 views

Why do some TSOP1738 have a metal cross over their window?

Why do some TSOP1738 have a metal cross over their optical window while some do not have this cover? Does not it obscure the view and shorten the range of the sensor? Does it have some positive ...
1
vote
1answer
563 views

Induction loop detector

I am trying to create an induction loop detector by following this http://www.allaboutcircuits.com/projects/metal-detector-with-arduino/ but apparently something is wrong on my side or I missed ...
0
votes
1answer
92 views

How do I build a micro controller based laser detector

I want to build a laser detector using a photoresistor and a pen laser. Ideally, I would like to increase the surface area that detects the laser beam, perhaps through refraction or diffusion. I'm ...
4
votes
3answers
7k views

Conversion from dBm to Volt/ meter

I have no experience with electronics but I have a question. Actually I'm using a circuit for a project that is able to measure RF power at its input in dBm; the circuit provides the integration of a ...
1
vote
2answers
2k views

Does a simple bug detector detect electric field or magnetic field?

Hi. This is a very cheap and simple bug detector that is supposed to make sound when it detect RF signals between 100Mhz-2600Mhz. I found out that it doesn't do what it supposed to do,since its ...
0
votes
1answer
114 views

Understanding resonance detectors

I'm exploring an old device that detects RF frequency. It has a generator of bipolar spike pulses +-1V interleaved by 0V sections, diodes and antennae (L1). simulate this circuit – Schematic ...
0
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1answer
91 views

How to detect/monitor AC power

I'm attempting to build a system to help my Father-in-law monitor the power to his house. Here's the details of his problem: He lives in the woods where power is somewhat unreliable so he has a whole ...
1
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2answers
2k views

Falling and Rasing Edge Detector

I will use a motor adapter in my design.This motor adapter doesn't have a spice model. Therofore I will design inside structure of this adapter. In this motor adapter has a delay and xor gate part.I ...
2
votes
1answer
332 views

High voltage led detector

I need a circuit to indicate if the DC voltage across two points is exceeded a certain High value (350 V) by using LED as an indicator. For example if the voltage is 355 V then the LED will light,but ...
1
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0answers
320 views

Dark detector with 555 timer and output pin has a LED

I am a complete novice and I had done it in a hurry with my kiddo around. I have redrawn it, with the values I used. The circuit works. Also between pins 6 and 7, if I use a 100 K/10 K it works. ...
1
vote
4answers
2k views

High Frequency (16 Mhz-48 MHz) Peak Hold/Envelope Detector Circuit?

I'm trying to make a peak hold circuit for a very high frequency bandpass filter that needs to be able to operate at 16 Mhz, 40 Mhz, and 48 Mhz. I've singled out the peak hold part of my overall ...