8
votes
Active RF signal repeater
First of all, your transmitter A would be illegal. And any conductive surface reflects electromagnetic waves; at 10 MHz, a sufficiently large metal sheet would do; there's no point in an active ...
- 96.8k
6
votes
Accepted
Will I run into issues if I connect a shunt 50 ohm resistor over a high impedance input pin on an IC?
Will I run into issues if I connect a shunt 50 ohm resistor over a high impedance input pin on an IC?
One result that may or may not be an "issue" is that the voltage at the high impedance ...
- 25.3k
4
votes
Can we use telescopic antenna for RF receivers?
Portable AM/FM radios and televisions with telescoping antennas used to be extremely common, these are receivers.
Spring coil antennas are used when you want the antenna to be short while in use, ...
- 25.1k
3
votes
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What is the optimal way to place a BNC connection point on a printed circuit board?
The four outer pins are connected the coax outer conductor and also serve as mechanical mounting, and all four should connect to PCB RF ground plane (which might be same as power ground). The signal ...
- 335
2
votes
How can a Class E Power Amplifier be built and experimented with safely?
basically be very carefull Follow the same advice given to those working with vacuum tubes. rubber shoes and one hand behind your back.
- 34.6k
2
votes
Accepted
Are there any LTspice models for OP AMPS with GHz bandwidth?
You will get opamps with GhZ BW. This is one of them.
Spice models are available at "Tools & Simulations 2" section.
You can import that spice models to Ltspice
- 2,593
2
votes
Generating Sinewave with PLL
my question is whether sinewave output is possible on an arbitrary PLL chip like the CD4046 or ADF4360.
Some PLLs integrate the VCO, others don't. Especially RF PLLs tend to, and often the output of ...
- 96.8k
2
votes
RF ground capacitor broken off on Raspberry Pi 4 - How does it affect performance?
Traces crossing a slot or opening in ground plane, is a great way to create an antenna.
It's likely these are small value capacitors (a few pF) to adjust the tuning of the slot antenna. It may still ...
- 39.6k
2
votes
How to sample current in high-kHz to low-MHz
There are several important parameters you don't specify, but generally, this looks like exactly the sort of thing that wide-bandwidth current transformers are made for. Pearson (no affiliation) is, ...
- 35.2k
2
votes
Where to find/learn standard meaning of ω or φ, etc., in RF circuit design
The publications of the ARRL are a handy source of the information that you are looking for at a level you should be able to understand especially since you have a ham license. Start with the ARRL ...
- 16.1k
2
votes
What is the purpose of this table on RF remote controls?
That "table" is to mark the manufacturing date.
"23" "24" "25" are for the years "2023" "2024" and "2025."
The other numbers are ...
- 72.5k
2
votes
How can I slow down the rise and fall time of a power MOSFET without adding a delay before the switching begins?
No, you cannot. That's simply logically impossible: you want an N ms rise time.
Because the rise can't start before you press the button (otherwise, your circuit would need clairvoyance) the rise can ...
- 96.8k
2
votes
12 channel remote control: 4-pin IC for 12 buttons: How?
The 4 inputs are in binary. When you press any button, it both sets these 4 inputs to some value and powers the chip.
The diodes are used to set the 4 input pins based on which button you pressed. ...
- 159k
2
votes
Will this FM transmitter work?
I would at least suggest a high-frequency ferrite bead or resistor in series with the base if using an RF transistor.
Using anything beyond MMBTH10 is overkill and inviting trouble, really. It's not ...
- 39.6k
2
votes
Accepted
How can I simulate an RF signal as received by an antenna in LTspice?
Yes, to all, with the caveat that (4) will take a very long time as transient simulation proceeds incrementally, as discussed in another recent question. And consequently might not be very accurate (...
- 39.6k
2
votes
Accepted
Why do direct conversion receivers amplify only after mixing?
I understand that we want to defer some of the amplification until
after the final filtering, so that we amplify only the signal, and do
not have nonlinearities and intermodulation to deal with, and ...
- 26.7k
1
vote
12 channel remote control: 4-pin IC for 12 buttons: How?
When you look at the logic table on P.2 of the datasheet, you'll see that for certain combinations of pins getting pulled high, you get specific data output. You can pull multiple pins high with a ...
- 96.8k
1
vote
Accepted
Will this FM transmitter work?
Made with microcap v12.
Something like this could be "used" ... As pointed out by @Marcus Müller.
It requires some add-on on the resistor values specifically adding "parasitic" ...
- 14.5k
1
vote
RF Microstrip trace polygon
Whatever you do, make sure you pay attention to the geometry of the stackup. If you put a plane above and a plane below, the transmission line changes from a microstrip to a stripline. Notice the ...
- 84.8k
1
vote
Accepted
RF Microstrip trace polygon
do I need to apply a ground polygon on the top layer side of the PCB or not?
To make a microstrip transmission line, you do not.
And if you do, you should keep the top layer ground region well away ...
- 131k
1
vote
Accepted
P2P communication: maximum range for low power & low bandwidth
You read about LoRa, so I'd guess you already stumbled upon the answer: faced with the problem that a low-power transmitter can't get data reliably across a channel of large distance, you reduce the ...
- 96.8k
1
vote
Accepted
Telecom Lines Conducted emissions noise travel
Presumably, no CM current in the Ethernet port means no ground current, and lifting it shouldn't make any difference.
This is an unverified assumption, however. A current clamp on the ground ...
- 39.6k
1
vote
What is inside of a typical RF transformer?
They make RF transformers that don't have a cover over them, so you could look at some of those. The covered ones will be the same sort of thing but with a bit of plastic or ceramic around them.
There ...
- 25.1k
1
vote
Transmitter parasitic drainage
Looking at the circuit board you can see that VDD goes through D1 and then to the pushbutton. But it also goes up to U1 and some other components, so most likely U1 is powered all the time and an ...
- 25.1k
1
vote
S-parameters of a matching network
You need to distinguish between the use of your network, and what you might do in measurement, design and verification.
In use, of course its output will be loaded in a nominal 200 Ω. If you want to ...
- 169k
1
vote
Cranes operating on 433 MHz remotes experience shutdown
The vendor is perplexed by these actions.
TL;DR: The vendor doesn't have the competence necessary to make those machines.
You'll need a consultant electrical engineer who will do the vendor's job ...
1
vote
Question About Utility Company Antenna Power/Radiation Concerns
That's not a lot of power, 2 W is half what a typical two-way portable radio would output. If the radiated power is 15 W that means that the antenna would have gain, roughly
$$ Gain = 10\times log(15~...
- 25.1k
1
vote
Accepted
Why wouldn't one use a DAC for an RF transmitter?
Are you thinking that this isn't done? It certainly is.
https://en.wikipedia.org/wiki/Direct_digital_synthesis
A basic Direct Digital Synthesizer consists of a frequency reference (often a crystal ...
- 2,930
1
vote
Accepted
How can a Class E Power Amplifier be built and experimented with safely?
OP's circuit does generate voltage spikes at MOSfet drain that can considerably exceed the DC supply voltage. Switching current off quickly to an inductor is the cause.
The circuit fragment of the few-...
- 26.7k
1
vote
Understanding impedance matching in RF PCB applications (STM32WB55)
Technically a shunt capacity of 0.6pF (or an equivalent, short 50 Ohm transmission line stub) would already be enough to make the output impedance 50 Ohm:
The component values for the matching ...
- 651
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