Questions tagged [reference]

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Is there sufficient 'ambient hum' to obtain a 60/120 Hz reference wirelessly?

In a typical urban (USA etc) setting, we seem to be awash in 'powerline hum'. Has it been done, or could it be practical, to recover this to get a wireless reference for a battery-powered system, like ...
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3 votes
3 answers
80 views

Should ADC reference pin also be a kelvin connection?

Reasking this question with a proper schematic: I am doing a ratiometric measurement of a Thermistor. The thermistor is located over 5 metres away from the ADC and all other components. This is going ...
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  • 75
-1 votes
3 answers
60 views

CMOS active crystal oscillator output voltage uncertainty

I want to use SG7050CAN CMOS active crystal oscillator as reference input to ADF4106 PLL. The input voltage level is 0.8/AVDD Vp-p min/max. Now, the SG7050CAN datasheet says, it's low voltage is 0.4 V ...
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  • 49
0 votes
2 answers
72 views

CMOS active crystal oscillator load capacitance, to be used for PLL reference

I do not have a clear idea of what load capacitance is. I am looking forward to use the ADF4106 PLL with a ~580 MHz VCO to synthesize the frequency. For the reference input to the PLL, I wanted to ...
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  • 49
0 votes
1 answer
309 views

Can I mass delete REFs from components in Kicad?

I have a PCB, and it can't nearly fit all of the REF markings on F.SilkS and B.SilkS. I want to just make my own for a few components, e.g. I would write "R1-R16", rather than "R1",...
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4 votes
2 answers
2k views

Resistor in shunt regulator not following Ohm's law?

I was reverse engineering a power tool battery charger (21V SMPS) that derives its 5V rail from a simple shunt regulator, employing a TL431 programmable precision reference and a NPN transistor, as ...
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  • 775
0 votes
1 answer
61 views

Driving 18 Thermistors in parallel

I am designing a circuit that needs to have 18 thermistors to measure the temperature at various points. The thermistors are 2metres+ away from the ADC Usually when I power a thermistors I use a Vref ...
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  • 75
0 votes
1 answer
59 views

TP4056 custom PCB battery reference voltage

I have a custom PCB where I implemented BMS system based on TP4056 from a 5V regulated solar power source. Everything works as expected regarding battery charging and output but I am encountering a ...
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0 votes
1 answer
42 views

Driving Delta-Sigma ADC with reference clock output from MCU

I am sending out the PB clock (32MHz which is PLL multiplied) generated from the internal FRC on a pin to feed into an ADC as a master clock after probing it at 32MHz. This is what I see. It doesn't ...
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0 votes
2 answers
164 views

Which is better for an adjustable stable reference voltage output?

I have two methods of achieving this and am trying to decide which one will be a better option for a stable output. The supply voltage is a linear regulator output, so it is pretty much constant. ...
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0 votes
1 answer
87 views

Reference clock in FM receiver chips (si4735)

The datasheet is mentioning a 32678 Hz "reference clock" (RCLK) input. It appears to be a well known thing in this type of ICs because it's highlighted in the list of features. I guess ...
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1 vote
0 answers
43 views

How to connect a ENC28J60 or ENC424J600 to a KSZ8091 PHY and from PHY to an unmanged strapped configuration to a KSZ8863 or other switch

How would one go about connecting MAC chip to a PHY and then to a switch for dual ports for daisy chaining? Rather be a strapped configuration for use in unmanaged mode so no need for MCU software ...
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1 vote
2 answers
89 views

[op amp - Gain current source - current reference]

I have a question about the formula to consider for calculation of the gain for the electronic bellow. Thanks for your support.
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2 votes
2 answers
239 views

How to solve a LED-resistor parallel with a resistor?

Hi there I am curious as to how you would solve this circuit to know voltage drops and currents. It came about from a previous question I had asked which showed my understanding was not quite what I ...
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0 votes
3 answers
74 views

Is there an equivalent EE term for "homeostasis"?

In biology, homeostasis is the state of steady internal physical and chemical conditions maintained by living systems. Is there an equivalent term for a circuit or electronic device? So that would ...
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  • 7,052
0 votes
0 answers
36 views

Current mirror not depending on power supply (BANDGAP design)

is there any topology that allows a current to stay constant on a current mirror when the power supply of the transistor is varied? I simulated a bandgap and the PTAT varies a lot when I the power ...
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0 votes
2 answers
318 views

Opamp Current Sink + FET circuit help

I've been trying to figure out a design someone made for controlling a precision high current LED, and it's got me in a bit of a pickle. For the life of me, I can't figure out this exact op amp ...
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0 votes
1 answer
225 views

Reference manual & Datasheet

I am new in the world of microcontrollers and I want to know the main differences between a Datasheet and a Reference Manual of a microcontroller and when do I use one and when the other.
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1 vote
1 answer
97 views

Question about feedback in a current reference

I'm studying the following Vbe-based current reference: The author of my book says: Observe that the circuit has two feedback paths around the gain stage. One positive, the other negative. ...
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  • 596
2 votes
3 answers
751 views

Self Biased Current Reference

I'm studying this circuit: The author of my book says that the purpose of this circuit, called "Self Biased Current Reference", is to generate a current almost independently of the supply voltage. He ...
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  • 596
0 votes
1 answer
87 views

STM32F429ZI reference voltage

I want to use the full output resolution of DACs (12bit) in the range of 0-1 Volt (and not in the range 0-3.3 Volt). I see there is a pin VDD in this board (STM32F429ZI), please help me to understand ...
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0 votes
1 answer
65 views

Series voltage reference output voltage

What is output voltage of series voltage reference IC (for example MAX6100) when input voltage is below minimum input voltage? Is it zero volts, or something else? Didn't find answer to this from ...
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0 votes
1 answer
88 views

Wheel heading using PWM

I have a general question which im not sure how to implement. Suppose that a car is driving on a straight road and it starts doing some maneuver. Due to this maneuver the driver moves the wheel ...
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  • 1
2 votes
1 answer
222 views

Selecting the equipment with the optimal 10 MHz reference

In a larger testbench I have 5 synchronized instruments (signal generators, ARBs, VSAs etc). I am trying to decide which instrument to take as "master". I rule out the older/cheaper parts (Tektronix ...
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  • 1,208
2 votes
2 answers
1k views

10 MHz reference distribution (daisy chaining vs. BNC tees vs something else)

10 MHz is the quasi-standard for reference clock in measurement equipment. Most boxes have "REF in" and "REF out" or "10 MHz in"/"10 MHz out". In my case, I have a measurement setup consisting of an ...
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  • 1,208
2 votes
3 answers
280 views

Create small variations in voltage for opamp reference pin

Hello and thanks beforehand. I'm designing a circuit to measure 4 wheatstone bridges using 4 Analog Devices AD8422 in-amps. Now, i'm feeding the AD8422 output to a 3.3V ADC, so i'm offsetting the ...
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0 votes
1 answer
164 views

AREF Voltage same as VDD but through a reference IC

My project has 9V and 3.3V on the board. I would like to use a precision voltage reference IC for the analog reference on the MCU (MCU powered by 3.3V). The precision of the voltage reference IC is 0....
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  • 315
13 votes
3 answers
2k views

Copyright of reference designs?

I have been reading a design guide by TI which provides full schematics for their reference design seen Here. There is copyright stamped all over this document as seen below. I don't plan on using ...
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0 votes
2 answers
914 views

the voltage output and resistance of a potato

For an undergrad lab experiment on noise analysis in various electric power suppliers, I constructed a battery from a potato with Cu/Zn electrodes and measured the outgoing voltage. Now I want an ...
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  • 117
1 vote
3 answers
543 views

How an op-amp determines its output without a reference point? [duplicate]

I was struggling to understand how an op-amp determines its output without a reference point. The output of an op-amp is A * (Vni - Vi) Then let's say we have an inverting op-amp with a gain of 1000,...
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0 votes
1 answer
63 views

Measuring PSR of a current reference chip

Some Background: I'm designing a test board to characterize noise and PSR of a multiple voltages(1V) and currents(1uA) reference IC. The chip has a single voltage source. I use ultra low noise MUX ...
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2 votes
1 answer
75 views

A mechano-electro-magnetical control circuit

I came up with the following mechano-electro-magnetical control circuit. The system as depicted here is in equilibrium, i.e. the upper spring s1 is relaxed , the upper circuit is closed (C1 producing ...
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5 votes
1 answer
643 views

What do decimal/alphanumeric suffixes after a slash mean in a schematic cross-reference?

I'm looking at a circuit diagram for the ChipWhisperer, which is a tool for power analysis and glitch attacks. You can grab the full circuit schematic as a PDF, but here's an excerpt: What do those ...
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5 votes
4 answers
3k views

Capacitor after Voltage Reference "for stability"

I've got a lot of experience with rather "low-level" electronics (resistor networks, passive filters, basic op-amp circuits) and some experience with higher-level stuff like micro-controllers, but I ...
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3 votes
1 answer
498 views

How to connect a diy audio signal to my "expensive" audio interface

I'm a hobbyist and after some experimentation (around 4 years) I want to connect my signals I create on the breadboard to my expensive audio interface. Until now I was using the "mic" input on my ...
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  • 571
4 votes
1 answer
5k views

MOSFET Temperature coefficient

I'm reading a paper by Guillermo Serrano and Paul Hasler, A Precision Low-TC Wide-range CMOS Current Reference, IEEE JSSC Vol 43, no 2, Feb 2008. Link to paper - requires subscription to IEEE Xplore ...
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  • 12.1k
1 vote
6 answers
331 views

LM385Z-2.5 in series with voltage divider - voltage reference problem

I'm doing a simple circuit using LM385. In THEORY voltage measured on cathode of D2 should be 5V. And it is so, if R2 and R3 are not present in the circuit. So voltage divider from R2 and R3 across ...
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  • 157
0 votes
1 answer
106 views

Reference of component

I´m trying to repair my lock control in my car. And this board seems like the problem, so I want create a new board (exactly the same) based on this. But I facing a challenge: I cant determine what ...
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  • 101
1 vote
1 answer
177 views

How to learn designing electronic cicuits? [closed]

This is a soft question. I have completed my engineering in electronics discipline and unfortunately I still don't have proper idea of designing electronic circuits. But anyhow I want to clear this ...
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0 votes
0 answers
228 views

The precision of internal voltage reference in PIC

I am designing some circuit with PIC16F18345 and I need some voltage reference (±0.5% or better). I can add some external reference or use built-in internal voltage reference in that MCU (that means ...
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  • 5,177
0 votes
1 answer
595 views

Reference circuit design for UART on GSM module

I'm designing a small development board (from schematic design to PCB), centered around an ATmega32U4 MCU, and a Quectel M95 GSM module. I'm using the M95 Hardware Design Manual (http://www.quectel....
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  • 103
0 votes
1 answer
64 views

LL2263-14 ADC input range question

I'm using LTC2263-14 14 bit pipeline ADC in my application. However, I'm completely confused regarding the input voltage range, reference voltage etc. It has a differential input with an internally ...
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3 votes
2 answers
372 views

Active resistor for gain Control for reference pin in instrumentation op amp

I'm using an instrumentation amplifier (AD8421 from analog device) to amplify very small signals in magnitude from 20uV to 500uV max. the problem I have with this is that the signals might have some ...
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1 vote
0 answers
252 views

The Art of Electronics exercise 1.19 [duplicate]

I'm reading The Art of Electronics(3rd), and I'm just stuck with exercise 1.19. Here is the question: Explain why L∝n² for an inductor consisting of a coil of n turns of wire, maintaining fixed ...
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  • 319
1 vote
2 answers
334 views

Voltage reference sampled by ADC (12 bit) gives value that is off by more points than other measurements

I am using the TI REF3020 voltage reference (2048mV) in combination with a microcontroller in order to have a reference for voltage measurements. The microcontroller is powered by 5V (5.00V), the ...
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  • 187
1 vote
1 answer
100 views

Help me check the values for capacitors in a reference design

I have the following circuit diagram from documentatoin for an MC34167 which I'd like to use in a project. Am I correct in assuming the capacitors are all in pF? which would give me:- 330pF 4700pF 0....
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  • 13
0 votes
3 answers
84 views

auto-recalibration of a power supply through something stable over time? (thought experiment) [closed]

Highly accurate instruments with a calibration are quite expensive, and anything electronic will tend to change over time. The effects of heat and oxidation, and perhaps changes in the material due ...
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  • 1,599
1 vote
2 answers
382 views

Instrumentation Amplifier REF pin maximum voltage

I'm a spanish engineer student doing my end-of-degree project. I need to remove the offset of a strain gauges bridge and i'm trying to make the calibration automatic, using a DAC (digital to analog ...
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1 vote
1 answer
355 views

Precision shunt regulator failure behavior

I'm working on a project that uses an LM4040 precision shunt in order to obtain a 2.5 V reference voltage (in particular, I'm using the LM4040-N-25). My circuit is similar to the one shown below (from ...
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5 votes
2 answers
720 views

Why is it a bad idea to divide reference voltage only with resistors instead of using an op-amp buffer?

I'm planning on shifting the output of an AD8226 instrumentation amplifier by 'about' 0.5 volts using a 2.5 v precision reference and a voltage divider. According to the datasheet this is a bad idea ...
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