Er... Digital signals exist in the digital domain, by definition. There is nothing analogue about 0, 1, 0xdeadbeef etc.
Adding the time domain changes absolutely nothing of that.
Okaaaayyy... I'm a little busy packing a 454 for shipping to its new home, but of course I've built a Mod-5 using flip-flops. Normally need at least two transistors to make a discrete flip-flop, and then something for the reset, but I remember reading a Hackaday about a DTL circuit that uses a single transistor as a flip-flop, but as tested it was limited to under 1 MHz operation. Not sure if that's what you had in mind, or something more along the lines of "analog computer" design wherein "operations" are performed as a function of RC/LC,etc time constants and LF heterodyning.
The circuit bd139 showed indicated one way. I think (without verifying it) that the Tek 184 uses a different way. No flip flops involved, only "glugs" - to use the lovely and descriptive) term frequently found in high precision voltmeters.
I remembered seeing bd's circuit from a while back, but couldn't be arsed to dig it up.
In my defense, I'm a little preoccupied saying goodbye to an old friend that's been with me for decades, but I haven't treated very well of late.
The only difference between a PWM voltage and a serial comms signal is convention (what is the acceptable amplitude/duration) and the fact of sampling over a given time window. Both have to exist as analog signals first.
This concept is obviated by the fact that multi I/O pins on modern processors often treat both interchangeably; creating an alternate serial data channel by modulating a PWM out at given frequency and amplitude to send serial data, or sampling an ADC IN similarly to receive serial data.
Come on man; we're arguing over semantics & terminology here.mnem
*rummage... rummage... rummage...*
Er... Digital signals exist in the digital domain, by definition. There is nothing analogue about 0, 1, 0xdeadbeef etc.
Adding the time domain changes absolutely nothing of that.
Okaaaayyy... I'm a little busy packing a 454 for shipping to its new home, but of course I've built a Mod-5 using flip-flops. Normally need at least two transistors to make a discrete flip-flop, and then something for the reset, but I remember reading a Hackaday about a DTL circuit that uses a single transistor as a flip-flop, but as tested it was limited to under 1 MHz operation. Not sure if that's what you had in mind, or something more along the lines of "analog computer" design wherein "operations" are performed as a function of RC/LC,etc time constants and LF heterodyning.
The circuit bd139 showed indicated one way. I think (without verifying it) that the Tek 184 uses a different way. No flip flops involved, only "glugs" - to use the lovely and descriptive) term frequently found in high precision voltmeters.
I remembered seeing bd's circuit from a while back, but couldn't be arsed to dig it up.
In my defense, I'm a little preoccupied saying goodbye to an old friend that's been with me for decades, but I haven't treated very well of late. ![Undecided :-\](https://www.eevblog.com/forum/Smileys/default/undecided.gif)
The only difference between a PWM voltage and a serial comms signal is convention (what is the acceptable amplitude/duration) and the fact of sampling over a given time window. Both have to exist as analog signals first.
In that example, the 8-bit digital signal is transmitted by the modulation scheme you mention. The serial comms voltages are a first-order hold of the sampled digital signal.
There are, of course, many other ways of transmitting digital signals. A 64 bit digital signal could be transmitted on 64 separate frequencies e.g. COFDM, or as multiple amplitudes and phases e.g. 64QAM with added noise:
![](http://www.raymaps.com/wp-content/uploads/2011/09/Constellation.jpg)
This concept is obviated by the fact that multi I/O pins on modern processors often treat both interchangeably; creating an alternate serial data channel by modulating a PWM out at given frequency and amplitude to send serial data, or sampling an ADC IN similarly to receive serial data.
That is indeed
one implementation technology that is around
at the moment.
There have been many over the years, e.g. one from near where I grew up:
![](http://intelmsl.com/wp-content/uploads/2014/10/Screen-Shot-2014-10-20-at-11.16.50.png)
Come on man; we're arguing over semantics & terminology here.
It is a deeper distinction than that, and philosophically quite interesting.
But it isn't (pure) TEA, and while it may deserve a separate thread, it isn't too relevant to a TEA thread. (Not that direct relevance has been too important in the past!).
This probably should have gone into the 'what did you buy today' thread but I know how much everyone absolutely HATES nixie tubes. I was at my ham club's annual tailgate party and the president of the club offered this to me for $2.00. He said it wouldn't power up and he didn't check the fuse. When I brought it home, I did a quick check of the fuse and it was good. I was outttatime as there was much to do, so I played with it a bit today and found the oddball fuse holder knackered. I wasn't able to restore continuity, so I spliced in a an inline fuse holder I had and it worked. I will let it warm up and I will warm up my DMMCheck + and get some readings off of it. It does have the AC and Ohms converters and the read input. The case looks like it has been rode hard and put away wet. There are what appears to be rust lines on it, like a wet piece of equipment has been put on it and left to rust. Also, there was only 1 foot, 1 partial, 1 very small piece of foot holding the screw in place and 1 missing. I added feet to it so it at least sits up off of the bench. It was last calibrated 2/13/92 with the AC calibrated from 50 Hz to 50 KHz. After I check measurements, I will add more pictures and maybe even a peek under the skirt. Then there will be the job of trying to find a place for it. I don't really have a need for a pizza box but it does have nixies.
EDIT: After running a couple of minutes, it appears the 3rd tube from the right wants to display all the numbers. Any suggestions what to look for and does anyone have the service manual for it?
EDIT 2: Tube is fine. I wiggled it around as I couldn't quite get a grip to pull it and reseat it. Issue went away. I am thinking of spending $10 and getting the manuals and schematics from Artek Manuals.
I got an RTL-SDR Blog V3 kit a few months ago. I don't know if it's better or worse than the NESDR or others. Apparently there are knockoffs of the RTL-SDR Blog V3, so I bought mine from the RTL-SDR Blog's eBay store.
For software, I use it with SDR#. It seems the original SDR# URL now redirects to airspy.com. I'm not sure what that means. You can still get SDR# on their download page, but it seems to be bundled with other stuff, now.
I got the dongle primarily to be able to check if a transmitter (e.g., RF remote) is functioning. But, using it to listen to FM and shortwave works as expected, too.
RTL-SDR V3 is pretty good. A bit more expensive than the generic one but with the metal enclosure heat dissipation is a lot better (A problem to be able to lock the pll at different frequencies).
The creator of SDR# was eventually hired by AirSpy and is now developing software over there. SDR# is still available for free and you can use it with generic R820T based hardware (ex RTL-SDR V3).
For a overview of the different SDR platforms, check this link https://www.rtl-sdr.com/roundup-software-defined-radios/
Thanks for the info, Kosmic. I suspected some kind of acquisition or something.
How does the RTL-SDR do at lower frequencies? The NooElec NESDR is specced at 65MHz bottom end and they sell an up converter for covering HF and the lower end.
Most of them don't go below 24Mhz. This is due to the R820T chip. Was initially designed to receive digital TV and was suposed to only work between 42Mhz and 1000Mhz. Can actually do 24 - 1700Mhz
https://rtl-sdr.com/wp-content/uploads/2013/04/R820T_datasheet-Non_R-20111130_unlocked.pdf
The RTL-SDR V3 can do 500 kHz - 24 MHz via direct sampling. I haven't tried it, yet. From what I read, before this version, there was a hardware hack to enable it. No need to anymore.
I admit it, I have a case of 427A envy, so I was on ebay, you know, just looking around. From Israel comes this beauty, which was apparently stored in a bucket of water:
![](http://u.cubeupload.com/worsthorse/427abeatup.jpg)
The seller is asking a mere fifty dollars for it and will spring for shipping. Oddly enough, he included no photos of the instrument's interior.
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)
Then on CL and found this:
![](http://u.cubeupload.com/worsthorse/seriously.jpg)
Which was apparently found outside in a pile of trash. Based on the number of broken knobs, it must have been dropped face down at one point. The seller actually powered it up on a variac and said it didn't catch on fire. He is currently entertaining offers.
I admit that I am tempted by the 468. I think I have a problem.
I wonder if that 427A is from the infamous seller in that geo-location. Then again, it's in too good of a condition.
I wonder if the 427A description was lost in translation.
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ?
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
David
I wonder if the 427A description was lost in translation.
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ? ![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
David
Looks like it was used to measure the salinity of the Dead Sea. That is, by dropping it in and seeing how the calibration changed after drying out.
I found that many listings fall back on various... interpretations... of English to, let's say, more flexibly describe the product. It leaves the buyer open to various levels of wishful-thinking.
Well known house clearance dude down the road from me is selling a Tek 310A on ebay. He's said he will strip the valves out and send just those on the auction. I am going to attempt to save it before some valve ferengi gets it and it ends up in a skip
![Angry >:(](https://www.eevblog.com/forum/Smileys/default/angry.gif)
Edit: I skipped the 453. Didn't have time to go and get it in the next week.
I wonder if the 427A description was lost in translation.
This item is in very good condition
Just noticed the side frame is split.
Why is the condition listed as "New other" ? ![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
Probably careless copy+paste operations. It seems the vast majority of test equipment is posted as "New (other)" despite being described as untested.
Well known house clearance dude down the road from me is selling a Tek 310A on ebay. He's said he will strip the valves out and send just those on the auction. I am going to attempt to save it before some valve ferengi gets it and it ends up in a skip ![Angry >:(](https://www.eevblog.com/forum/Smileys/default/angry.gif)
Beware of the Valve Ferengi!
He forgot his tube earrings.
Yeah this dude:
![](https://i.imgur.com/KXGQUqH.jpg)
Hurry up and get it before the bastard strips the tubes out.
Yeah... I'd expect the insides of that to look like those pics from the Titanic; complete with aquatic life forms.
![Tongue :P](https://www.eevblog.com/forum/Smileys/default/tongue.gif)
mnem
"...ahnd 'ere you cahn zee... ze norzern auric zeebra muzzel, 'appily munching away on zome gold-plated contahct vingerrzz..."