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Questions tagged [tuning]

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Tuned RF circuit: How to minimise interference?

The circuit in Figure 1 is designed to detect an RF signal at f0=40kHz. For information, this will be a portable proximity sensor, worn on a cat's collar, so it has be small and light. The circuit ...
James V Stone's user avatar
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3 answers
94 views

If many radio waves can generate currents in the antenna ground circuit **simultaneously** I am wondering do they all get carried over to the tuner?

If many radio waves can generate currents in the antenna ground circuit simultaneously, I am wondering do they all get carried over to the tuner circuit?, but only the current whose frequency matches ...
Jack's user avatar
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0 answers
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DC/DC Buck Converter : Implementing Convenient Minor Alterations to Output Voltage

Question How can I perform precision minor output voltage adjustments when using a dc/dc voltage buck converter with high efficiency (including at light loads), without loss of efficiency and without ...
kando's user avatar
  • 437
0 votes
0 answers
105 views

Ziegler–Nichols method of PID auto tuning

I am working on a problem where I need to implement auto tuning PID control using Ziegler–Nichols method. Basically I want to control temperature using it. The PID has to be implemented with the ...
newbie's user avatar
  • 25
0 votes
1 answer
159 views

Why do PCB designers opt for serpentine tuning and switchback tuning over spiral patterns when addressing length matching in their designs?

I am currently researching the length matching problem in the PCB EDA domain and am curious as to why tools such as Allegro and Altium primarily use accordion, trombone, and sawtooth patterns to ...
David Lee's user avatar
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1 answer
319 views

Can I connect two PWM DC motor controllers in series to achieve coarse and fine tuning?

Can I connect two PWM DC motor controllers in series to achieve coarse and fine tuning? I would set the (2nd) fine tuning controller to midrange and then adjust the (1st) coarse one first. ...
LRHann's user avatar
  • 1
0 votes
1 answer
120 views

Is there a way to "indirectly" measure the position of a variable capacitor?

I am modifying the insides of a vintage radio. I wish to avoid damaging it or changing it as much as practical. Here is the insides of the radio in question: A primary goal is to measure the position ...
Duke Dougal's user avatar
1 vote
2 answers
98 views

Gating MOSFET with an antenna (adjust voltage to use only peak)

If we pulse a coil/tank circuit it's supposed to ring at it's natural frequency. We could use a pickup coil over a shared ferrite core or a straight antenna, connected to the gate of a MOSFET to time ...
juanmf's user avatar
  • 135
3 votes
0 answers
144 views

How to connect the VNA to RF transmission line for antenna tuning?

I am working on a 2.45 GHz(Bluetooth) project. the design has a Chip antenna with 50 Ω impedance trace to connect antenna and chip. I intend to tune the antenna impedance using the Pi network using ...
Sussy's user avatar
  • 31
6 votes
1 answer
352 views

Analog television: What is the difference between the first IF and second (demodulated) IF?

I am trying to understand what kind of changes occur to a signal in the chips which sit between the tuner and, for example the FM audio demodulator. Take the attached example - the TDA2546A. It takes ...
Matthew Millman's user avatar
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1 answer
182 views

Resonant RF transformer using a piece of wire (no capacitors)

I'm curious if it is possible to build a spark-gap Tesla coil without using capacitors at all. Basically, treating the primary and secondary as TX/RX antennas and cutting them to proper length so that ...
elgroovy's user avatar
-1 votes
1 answer
125 views

VCO tuning voltage range starting from higher than 0 V

I have seen some VCO datasheets. In every datasheet, I see that the tuning voltage range starts from some value above 0 V (like 0.5 V, 1 V etc). So, what would be the frequency at 0 V? And why do they ...
shafik's user avatar
  • 59
0 votes
4 answers
1k views

Difference between tuning and matching for transmitter/receiver circuits

I would like to find a coherent answer to following question: What is precisely the core difference between tuning and matching in HF electronics, especially in design of transmitter/receiver circuits?...
user267839's user avatar
1 vote
1 answer
195 views

DDS - find optimal size for LUT, PHACC and sampling freq for application

I had the following question. About the topic of DDS you can find a bunch of information on the net and i think i understood the basics relatively well. You use a lookup-table with stored values of ...
Rabobsel's user avatar
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3 answers
472 views

Old tvs, how did storing settings work, and what changed in the tv when we tuned a channel?

I don't have an EE background, but I would like to understand some aspects of old TVs. When we tuned channel what exactly changed inside the tv. Was there a circuit card in the tv where something ...
user394334's user avatar
1 vote
1 answer
313 views

How does one choose a resistance for an AM radio antenna receiver tuner?

[![enter image description here][2]][2] I am using some pretty rough, brute force and novice calculations, so if anyone knows a nicer method I am happy to learn. I want to build an AM radio receiver ...
Adriaan Berger's user avatar
0 votes
2 answers
1k views

Variable Capacitor - capacitance vs. rotation angle

I have an Elenco AM / FM radio kit. For the AM section I am trying to figure out the relationship between the frequency shown on the calibrated dial and the angular position of the dial. For a ...
user34299's user avatar
  • 397
0 votes
1 answer
490 views

Calculating lengths of single-stub transmission line when all 3 characteristic impedances differ

Consider a transmission line circuit like the following but where \$Z_{o2}\$ was also unique (say \$Z_{o2}=7\,\Omega\$): I know how I would find \$l_1\$ and \$l_2\$ using smith charts: $$Re\left\{Y_n(...
Landon's user avatar
  • 177
1 vote
0 answers
215 views

How to design a PI controller for fourth-order transfer-function?

Fourth-order systems may render very complex characteristic equation that are difficult for tuning. Is there any method to tune controllers for these systems easily?
Domino's user avatar
  • 41
5 votes
2 answers
643 views

Why do AM radio stations have secondary frequencies?

First thing I'm sorry if this question sounds too much beginner-ish. I don't major in electrical engineering so I may lack the basic knowledge. I have been noticing that, while tuning my AM radio, ...
MattCat15's user avatar
  • 151
0 votes
2 answers
409 views

Antenna Tuning for Source Impedance not equal to 50 Ohm

I have designed a setup for 433.92MHz wireless device (a key fob). The source impedance is not equal to 50Ohm. The load impedance may or may not be 50Ohm depending upon the choice of the antenna. For ...
spockshr's user avatar
  • 141
0 votes
0 answers
31 views

RC quality factor increase

simulate this circuit – Schematic created using CircuitLab This circuit has a bandwidth of 0.9Hz but I want even lower bandwidth. I have this RC tuning circuit. If i had an RLC tuning circuit ...
Jelly Strawberry's user avatar
1 vote
0 answers
58 views

Tuning PID Controller with high precision

I'm learning control theory at university and I have to design PID controller for this object G(s) = 10/s(s+1); But my teacher requires settling time <10s and %overshoot <=2% Anyone can suggest ...
John Smith's user avatar
0 votes
3 answers
527 views

Antenna tuning for a multi-band antenna

I have a PCB antenna that supports multiple band antenna. https://www.johansontechnology.com/datasheets/0830AT54A2200/0830AT54A2200.pdf We also have a tune circuit before the antenna as recommended by ...
Bharav's user avatar
  • 782
2 votes
1 answer
281 views

RF Jumper at 2440MHZ

I need a series component to isolate a 2440MHZ antenna for testing purposes-- it can either be a a high quality 0402 RF capacitor (Johansen) or a zero ohm resistor. The series component will remain ...
BHS's user avatar
  • 145
1 vote
3 answers
382 views

Radio tuning capacitor

In a radio tuning capacitor that consists of semicircular plates , are the plates connected in series or in parallel ?
user207332's user avatar
1 vote
1 answer
804 views

Antenna tuning & impedance matching, do i need to connect the IC?

I want to make a pcb rf trace to use it as an antenna, for a bluetooth IC. I have already studied the basics of impedance matching and antenna tuning, smith chart and antenna clearance. The specific ...
Basilisvirus Instrector's user avatar
1 vote
1 answer
132 views

Do algorithms exist for tuning microwave filters?

I'm a systems engineering student and I have taken a summer job at a company that manufactures various microwave filters, my role is to "try" improve and standardise their processes in order to ...
8TrackRobot's user avatar
-2 votes
2 answers
105 views

My antenna tuning component values worked on a fresh board previously. Now they're not working. What could be causing this?

This is one of those hardware questions that's making me bang my head against a wall. About six weeks ago I spent a day tuning the NFC antenna on my board. I ended up using ~71pF of shunt capacitance ...
macinblack's user avatar
0 votes
0 answers
31 views

Finding the gain difference for a ultrasonic assembly

I am tuning an ultrasonic assembly for a welding application and tuned the system to operate at 41kHz according to the oscilloscope. The transducer operates at 40kHz, when calculating the gain with ...
Neamus's user avatar
  • 281
7 votes
1 answer
1k views

Where to connect the VNA during matching network tuning

I'm trying to design the matching network between an antenna and its transmitter, running at 868MHz, as shown below. There's probably about 20mm between the transmitter output and the Pi network. ...
Amr Bekhit's user avatar
  • 1,298
0 votes
0 answers
138 views

MOSFET Switch for Tuned LC Tank

I am trying to implement the circuit as shown below. I essentially want to be able to control the gate voltage of the NMOS to change the resonant frequency from 5GHz to 2.5GHz. For a transistor size ...
user367640's user avatar
1 vote
0 answers
589 views

Magic Eye Tuning Tube Variable Negative Voltage

I am thinking about several applications of magic eye tuning tubes as display pieces and had a question about their operation. I have attached a sample circuit from a datasheet for an EM84 tube. I ...
Efram Goldberg's user avatar
0 votes
1 answer
205 views

Some questions regarding impedance matching and tuning

For maximum power transfer in a circuit impedance matching is performed: Similarly from the transmitter antenna to the receiver/load one can think the total impedance from antenna to the receiver as ...
user16307's user avatar
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