Measurement is the assignment of numbers to objects or events. All measurements consist of three parts: magnitude, dimensions (units) and uncertainty.
1
vote
2answers
75 views
Measuring large differential voltage
I have a high voltage power supply for an electron beam system. The voltage regulator is an old analog system that works via a simple comparator and reference signal from a POT. My problem is the ...
1
vote
2answers
88 views
measuring transistor beta (Hfe) - Ib anomalies explanation needed
I've been struggling with details of building accurate (+-1% tolerance max) beta meter. The simplest idea I came with went to a diagram as shown below, with R set to a value providing 0,01mA current ...
3
votes
1answer
104 views
How to detect low battery of a lead-acid battery?
I've heard that discharging a lead-acid battery to 0% is bad and wears it out. I have a 10Ah 12v lead-acid battery, is there a circuit to tell me when the battery is low?
2
votes
3answers
143 views
How do I calculate the input voltage based on an ADC reading?
+UB is a 12V power supply. I have to find the voltage on U_KL30.
I take this U_KL30 as an input at PortA<1> of my MC9S08DZ60 and use an ADC to get a ...
4
votes
1answer
89 views
Measuring very small changes in resistor network using current source
I am trying measure a very small change in resistance (approximately .400 Ohms), due to the the effects of connecting a large resistance in parallel with a network of smaller resistors essentially ...
1
vote
3answers
102 views
Selectable Voltage Divider Optimal Switching Point
I've built a circuit to measure an unknown resistance (over a large range) which is basically the following:
simulate this circuit – Schematic created using CircuitLab
Range_Select_1 and ...
1
vote
2answers
154 views
How to measure capacitance without LC meter?
I would like to use capacitors salvaged from old electronics, but I currently don't have a LC meter.
What would be some really simple circuits, that would convert capacitance to something I can ...
3
votes
1answer
49 views
Effect of switching noise on a handheld measurement device
I'm planning to make a handheld LCR meter (plus more) based on Cypress's PSoC 5LP chips. One of their many features is a built in boost converter, which seems an attractive prospect, since it would ...
6
votes
4answers
170 views
Does it make sense to measure components in-circuit in order to prove non-functioning?
When an electrical circuit is not working properly does it make sense to use a multimeter to measure/test the individual components in-circuit (without soldering them out), e.g. measure transistor ...
3
votes
2answers
244 views
Input and Output Impedance of a BJT
Hi I'm new to electronics and I would like to know how to measure experimentally the input and output resistance of the following common emitter configuration. I have access to a voltmeter, signal ...
6
votes
3answers
132 views
What effect does bit depth of an ADC have on noise floor, THD, or any other specification?
I was told recently that there is a direct relationship between bit depth of a measurement adc and minimum measurable noise floor, which in turn affects accuracy of THD measurements of DUT. I'm afraid ...
4
votes
4answers
153 views
devices for measuring tension or detecting “slackness” in fishing wire
How might I go about measuring the tension in a line of fishing wire? I'm mostly interested in determining when the line is in tension vs when it's slack.
The application is a boat-mounted ...
5
votes
0answers
90 views
How to use SCPI on HP33120A via RS232?
I have old Hewlet Packard 33120A function generator (it should be the same type as Agilent 33120A) and I would like to control it with MCU (ATMega). The generator has RS232 and use SCPI commands.
I ...
5
votes
3answers
103 views
How to measure the capabilities of a wall adapter?
I purchased this from dx.com. The specs on the device claim 1A@24V.
The device exhibits 24V at no load on pins +4,5 and -7,8. According to Wikipedia, this is called a passive power injector. I tried ...
0
votes
3answers
140 views
sEMG with ADS1299 from TI
What else besides an ADS1299 from TI and a 32bit microcontroller (like Teensy or Electric Imp) would I need to get an sEMG signal?
The ADS1299 is a "low-noise, 8-Channel, 24-Bit analog front-end for ...
1
vote
0answers
72 views
Testing the Amp ability of a copper wire in an automotive environment
A question posed on a forum for the pico scope relates to testing of the wiring for a load bearing circuit. For example a circuit with an electric motor, lamp, heater element, fuel pump, etc. They ...
0
votes
3answers
104 views
Detect if a microwave is running
At work we have a alcove hidden from direct view with a wall covered in "standard" domestic microwave ovens (MO). You put in you food there and then you join your fellow colleges chatting; after a ...
0
votes
1answer
97 views
attiny85 drops voltage level on an output pin… why?
I am in the process of building a wireless transmitter that is driven by an attiny85. I have programmed the MCU to encode the data using Manchester encoding and I have used an oscilloscope to show me ...
0
votes
1answer
134 views
Lux meter - Voltage range problem measurment
I'm about to build a Luxmeter. I want it to give me a respons of 1mV/lux and be able to detect 10.000lux.
Here is part of the solution I'm about to use (4. Luxmeter): ...
0
votes
1answer
106 views
When can a characteristic curve (here an amplifier) be considered linear?
I have built a difference amplifier and I have a pretty linear characteristic with a coefficient of determination of 0,9999478 (by a linear regression). Is it enough to say it's "pretty linear" (I ...
3
votes
3answers
470 views
Detecting dry-running of water pump
What are some reasonably reliable ways of detecting that a water pump (electrical motor based) is "dry running", i.e. no water is passing through the pump either because there is no water available at ...
4
votes
3answers
430 views
Water level detection, where water is somewhat polluted and has significant dissolved salts
Found this excellent QnA here which provides several options for measuring or detection water-level. For my case, it is enough to differentiate 4 levels of water (very low, low, middle, full), of the ...
1
vote
0answers
84 views
Need help with generating a bi-phasic current
I'm trying to generate a symmetric biphasic current pulse using a Grass S88 Stimulator.
Here's a diagram:
SG is a signal generator with two outputs, S1 and S2, which are generating a periodic ...
4
votes
3answers
188 views
Resistance to Digital converter
I am trying to make a digital ohmmeter on a parallel port interface that can measure resistance with at least 95% accuracy. I have tried a 555 timer monostable assembly which generates a pulse with ...
3
votes
4answers
252 views
Can DAQ devices be used as Oscilloscopes?
Recently, I took computer architecture course, and got interested in analog electronics. At present moment, I can't afford good USB oscilloscope such as Agilent or Cleverscope (though, they are not ...
3
votes
2answers
140 views
What would make a laser measuring device more accurate
I was looking a varioos laser measuring devices (laser tape measures). Most of them seem to be accurate within 1/8th of an inch. I'm wondering what the limiting factor for accuracy is. Is it simply a ...
-2
votes
1answer
62 views
How to obtain safety testing equipment? [closed]
What is the best way to obtain (buy or build) mandatory safety testing equipment? Eu standards specify a "reasonable" amount of equipment in order to sell your home made equipment (selv and other ...
3
votes
3answers
215 views
Is there a device to measure distance to a live wire through bone-like material?
Is there any electronic device that can measure the distance from a point in space to a wire with very low voltage running through it? The measurement of concern would be approx. 3 to 5mm . Its ...
0
votes
0answers
56 views
measuring vertical movement in a container
I am looking for a non-mechanical means to measure the descension of a plate within a container about 3cm by 15cm by 7cm. The plate is not terribly well guided so there is a need for a lot of room for ...
2
votes
1answer
684 views
How to properly set up a multimeter to measure the power consumption of a computer?
From what I understand, a multimeter can be used to measure the resistance in in a circuit. Multiplied by the voltage, measured in the same circuit, I would get the total power consumption. Is this ...
1
vote
3answers
216 views
Does calibration involve fixing electronics or mechanical part?
My question is not 100% related to electronics design but it might be because I don't know the answer.
I'm writing a simple research on anemometer calibration. The thing is all the resources I found ...
2
votes
1answer
148 views
computing shunt resistence for a microammeter
Let's suppose I have a dc microammeter with a range of 100 ua that claim to have an internal resistence of 1Kohm.
I want to use this instrument to measure a range of 1A. I'm assuming I need a shunt ...
1
vote
1answer
94 views
Power and energy measurment for embedded system -help needed
I am trying to measure the power consumption of a low power embedded system. As the embedded system consumes current in random pulses from the battery pack, I am using an oscilloscope to analyze the ...
2
votes
1answer
218 views
How to measure three resistors in a triangle
I have three unknown resistors arranged in a triangle (a delta) and need to determine one of them, which is on the order of 100x larger than the other two, in a measurement circuit. I'm wondering if ...
1
vote
1answer
254 views
Can you tell me how the op-amp in this DMM circuit works?
This is a autoranging DMM circuit. Specifically I would like to know what the lower op amp is for. It seems to be a non-inverting configuration with the (+) terminal at ground, but I don't what it ...
4
votes
2answers
279 views
Current measurement in component level of an embedded system
I have an embedded system with a MCU, GPS module, GSM module and TI module. The project is largely depend on the total battery consumption. In order to characterize battery consumption, I have to ...
4
votes
3answers
580 views
How to build impedance meter
I want to build impedance meter for measuring input-output impedances of audio amp stages.
Does anyone have experiences with such projects. I want to measure stages while running (hot measuring) so ...
2
votes
1answer
88 views
Measuring distance at angle
I have a question, I want to measure a distance from an object of unknown shape and material, and I want to measure it under different angles, I want to measure a distance to just one specific point ...
1
vote
3answers
2k views
Measure weights with arduino
I want to measure weights with arduino. After the measurements, i want to analyze the weight data of the measured objects.Precision is not very important, but it should be work in the range of 10 to ...
13
votes
10answers
2k views
Ways to determine polarity (dc) without a meter
I came across this question about how to figure out the polarity of a cell phone charger without a meter. This made me think of what methods you could use to figure out the polarity other than using a ...
0
votes
2answers
158 views
RFI/AC Filter Rejection for Instrumenation Amplifiers
I'm attempting to measure the voltage developed across a very long piece of cable (upto 500m bundle). The issue is that the cable picks up a lot of noise from nearby radio stations and also has a 50 ...
2
votes
1answer
194 views
What is the effect of Saturation on a Ferrite Bead Inductor?
This circuit shows the "current channel" of an energy meter.
IA_IN are the two inputs for a shunt (typically 250 uOhms) while TP1 is the connection to the energy measurement IC, which uses the 3.3 ...
6
votes
1answer
87 views
Torque measurement device calibration
I don't know if I'm at the right place to ask this question but here is my trouble :
I'm trying to find a good way of calibrating a electronic device used to measure small torques (0 -> 25 mNm).
...
17
votes
4answers
707 views
How can I measure the temperature wirelessly inside a piece of meat?
For a cooking experiment, I'd like to be able to measure the temperature inside a piece of meat while it's being cooked. Due to the mechanics of the cooking process, it's going to be difficult to use ...
6
votes
2answers
327 views
How to measure power consumed by mains device
I would like to measure the power consumed by a mains device. I have heard that it's not as trivial as simply measuring the average current, as the device may be resistive, capacitive or inductive, ...
4
votes
2answers
458 views
Will this ADC circuit work as intended?
Here is revision 6 of the circuit. Hows it look? :)
(This is an ohmmeter circuit. It measures resistances from 1 to 10M ohm with an accuracy of 1%. The resistor (not shown) is measured between J5 and ...
1
vote
1answer
164 views
MCP 3909 energy metering chip problem
What I've:-
I'm using MCP3909 energy metering chip ,
I'm setting this chip in pulse output mode which gives output pulses proportional to the real power .
The used shunt resistor is 200 u Ohm .
...
4
votes
4answers
339 views
How to make single ended voltage measurements
I’m in the process of setting up a test rig to automatically measure and test induced PCB voltages. The device I’m using (we’ll call it the meter) makes single ended measurements. The PCB output ...
0
votes
0answers
120 views
Is there an out-of-the-box solution for measuring low resistances?
I have a microprocessor project where I need to measure resistances between .1ohm and anywhere above 10ohm and I need to do it about 1000 times per second. Guessing from the number of tutorials I've ...
2
votes
1answer
154 views
Is it possible to build something that can measure water and oil in a tank with out being in the tank?
Say you have water and oil in tank....Is there any thing out there that can tell me how much water is in the tank and how much oil is in the tank???
