Home
Help
Search
Login
Register1
Projects, Designs, and Technical Stuff / Re: I made a 50 ohm load with BNC connector, Is this correct?
« Last post by daisizhou on Today at 04:25:51 am »How can I test it?
Recent Posts
2
Projects, Designs, and Technical Stuff / Re: I made a 50 ohm load with BNC connector, Is this correct?
« Last post by Kim Christensen on Today at 04:22:58 am »I've made similar. Mine were good up to about 1Ghz when tested for SWR with a VNA. Test yours and see.
3
General Technical Chat / Re: Future of computing & ai
« Last post by ballsystemlord on Today at 04:20:33 am »I'm convinced. This whole thing was written by an AI. Who else could come up with something so unusual?
And for those who aren't familiar with Judaeo/Christianity, there's nothing is the Bible or any other teaching about bubble building or any of the other stuff mentioned herein about science.
And for those who aren't familiar with Judaeo/Christianity, there's nothing is the Bible or any other teaching about bubble building or any of the other stuff mentioned herein about science.
4
General Technical Chat / Re: Know of any good books/sources of useful electronic schematics?
« Last post by ballsystemlord on Today at 04:16:13 am »You can consider magazines as well. This one has lots of circuits throughout the years. And it is fun to read.
https://www.elektor.com/products/elektor-archive-1974-2023-usb-stick-en
$125 USD + shipping from EU->US is quite a bit to spend on some magazines. I think I'll pass.
5
Computers / Re: Firefox 125.0.3 breaks odysee?
« Last post by radiolistener on Today at 04:15:57 am »just tried this site with firefox 125.0.1. It is very laggy, videos are shown with about 3-5 fps.
With Chrome it works much better.
I'm using linux on raspberry pi 4.
With Chrome it works much better.
I'm using linux on raspberry pi 4.
6
General Technical Chat / Re: Know of any good books/sources of useful electronic schematics?
« Last post by ballsystemlord on Today at 04:12:51 am »useful electronic schematics?Flybacks are a big field? Seriously? That's amazing.
That's too general. Discrete? Integrated? Analog? Digital? Power? Control? Audio? ... There are thousands of fields and millions of designs.
For example, flyback PSU is a big field all by itself.
I'm looking for beginner/intermediate books. Things beyond driving leds but not as sophisticated as building 9.5 digit DMM. But feel free to point out more awesome advanced stuff at your leisure. I can always refer back here later.
And those outdated books... I have a few of them and still have found useful ideas like this which is about 50 years old:That's good to know.
https://www.eevblog.com/forum/projects/scr-power-control-for-electric-blanket/msg5170533/
7
Projects, Designs, and Technical Stuff / I made a 50 ohm load with BNC connector, Is this correct?
« Last post by daisizhou on Today at 04:12:40 am »I test the RF signal.
I made a 50 ohm BNC interface resistor,I used 2 100 ohm chip package resistors in parallel.and mount them inside a BNC connector.
Can this be used?
Is it different from a standard 50 ohm load resistor?
I made a 50 ohm BNC interface resistor,I used 2 100 ohm chip package resistors in parallel.and mount them inside a BNC connector.
Can this be used?
Is it different from a standard 50 ohm load resistor?
8
Test Equipment / Re: Vevor SDS1104 for first oscilloscope?
« Last post by Muttley Snickers on Today at 04:11:54 am »If the price is right then a used SDS1104XE in good condition would still be worth serious consideration particularly for somebody on a budget. If the OP is not in a desperate rush for a scope then this would be my recommendation, cheaper than new and far superior to what they are currently considering.
I just saw someone buy a second hand SDS1104XE for 540 bucks+postage on aus ebay, so prices are not going down that much. New one is still close to 700 on AppVision. I think the scope market is just too slow in Australia and some people don't know about 800X series. We are still yet to see 800Xs here. Everybody else has them for sale but not Australia (and our friends across the ditch). Perhaps wait until the end of financial year to get better deals.
I think it's still way too early to access or speculate on what is considered a fair price for a second hand SDS1104XE in Australia, and even for those updating. In fact, some are probably more likely to hang on to their prior model for a while until they are satisfied that it is no longer needed and only taking up space.
Also, I wouldn't use ebay as a guide as there are likely plenty of buyers whose only focus is the purchase of a good oscilloscope at a reasonable price and perhaps not even aware there is a new series available as you pointed out. I can speak from experience when I say that not everyone who seeks certain test equipment reads or frequents electronics discussion forums for information, I never did anyway.
I hate giving out secrets and revealing my sources but the best place to keeps tabs on prices and more importantly find a well looked after pre-loved scope from a reputable person is here, and don't tell anybody else the prices might go up.
9
Projects, Designs, and Technical Stuff / Recommendations for commonly chosen ICs
« Last post by jbb on Today at 04:10:04 am »Hi all
I'm finally getting a design underway and have selected some of the major components. However, there are a few peripheral parts which I need to select. Can anyone suggest common / jellybean choices for the following:
Background: I want to build an Impedance Analyser to operate from 50 Hz to 10 MHz (and maybe above 10MHz in the future).
Current plan is to build an auto-balancing RF bridge. Drive voltage (Force +) and balance current (Force -) sine waves will be generated by two channels of an AD9106 quad Direct Digital Synthesis (DDS) chip and appropriate analog circuitry.
The remaining two channels of the AD9106 generate a quadrature LO which is then used to demodulate the measurement signals back down to I and Q signals with a Tayloe mixer (aka a Zero IF approach).
Unfortunately, the AD9106 uses a common DDS frequency for all four channels. The standard functionality lets you vary the phase shift and/or amplitude of each channel, but not generate a second frequency. Hence the initial plan above. (I am toying with a notion that it might be possible to manipulate the AD9106 into generating an output which is offset from the main frequency, but I'm not super confident it's possible.)
I admired the Teensy-LCR by WeTec, which tops out around 90 kHz. Moving up to 10 MHz should give me some visibility into the self resonant frequencies of home made transformers etc.
I'm finally getting a design underway and have selected some of the major components. However, there are a few peripheral parts which I need to select. Can anyone suggest common / jellybean choices for the following:
- An I2C port expander. I expect to have 2 of them on the same bus, so I'd like one with address select pin(s)
- A Digital to Analog Converter for DC level setting. I need something like 4 channels @ 12 bits, and all the options on DigiKey seem to be really expensive at the moment. I2C preferred, SPI would be OK.
- A clock multiplier to get from a crystal (say 10 MHz) to 180 MHz. I'm thinking the Si5351A...
Background: I want to build an Impedance Analyser to operate from 50 Hz to 10 MHz (and maybe above 10MHz in the future).
Current plan is to build an auto-balancing RF bridge. Drive voltage (Force +) and balance current (Force -) sine waves will be generated by two channels of an AD9106 quad Direct Digital Synthesis (DDS) chip and appropriate analog circuitry.
The remaining two channels of the AD9106 generate a quadrature LO which is then used to demodulate the measurement signals back down to I and Q signals with a Tayloe mixer (aka a Zero IF approach).
Unfortunately, the AD9106 uses a common DDS frequency for all four channels. The standard functionality lets you vary the phase shift and/or amplitude of each channel, but not generate a second frequency. Hence the initial plan above. (I am toying with a notion that it might be possible to manipulate the AD9106 into generating an output which is offset from the main frequency, but I'm not super confident it's possible.)
I admired the Teensy-LCR by WeTec, which tops out around 90 kHz. Moving up to 10 MHz should give me some visibility into the self resonant frequencies of home made transformers etc.
10
Repair / Re: Please help, how can I adjust this transistor?
« Last post by daisizhou on Today at 04:05:49 am »Do you mean the green connection like the picture below?
If it is connected like this, I tried.There is still a lot of interference, I mean human body interference.
If the test is forced, I am not sure whether the test results are accurate.
If it is connected like this, I tried.There is still a lot of interference, I mean human body interference.
If the test is forced, I am not sure whether the test results are accurate.