24 iulie 2014

Simple oscilator for testing cristals

Yesterday I was a little bored and I was staring to a box full of quartz cristals. I was wondering what frequency was, especially a very old one with russian marks on it. I know from an elder that the number on the Russian cristal is not the frequency but some sort of code. Stupid, eh?
After I contemplate various possibilities of transistor oscillators, I came up with a simple, reliable and versatile TTL configuration, "a classic" to say it simple.
It's a 74LS00 oscillator in series configuration, the schematics is pretty self explanatory.
Now I cand measure with precision the exact frequency of my 38.9 MHz crystals which, by the way, are overtone! I will make nice filters  for 12.95 MHz on long winter days!
Without a quartz crystal, it self-oscillate around 50 MHz with a very nice sinus wave!

The signals are from pin 6 and pin 11:

Self oscillation>
With a crystal:

21 iulie 2014

My laboratory I

Some are curious about my lab tools.

Well, I do have some stuff collected in years.
The most important tools in a electronics laboratory are the scope and the signal generator.
My scope is a AGILENT DSO 1014A, a four channel 100 MHz 2GSa/s scope. I wish it was a analog one but they are very big and expensive. Why my wish? Because you can use it on some measurements where a digital scope is useless due to alias issues.
This scope is a nice one but, in reality, is made by RIGOL :-) Either way, it's a nice piece of equipment!

Agilent's DSO1000A Series oscilloscopes deliver the performance and features you'd expect in a big scope - and the portability and low price you require in a small one. They've redefined the economy scope by giving you more: more signal viewing, more capabilities and more productivity.

Description from Agilent webpage:
Capture long time periods with high resolution
All models provide provide up to 20 kpts per channel of convenient acquisition memory standard. The scope will maintain high-resolution acquisitions even at slower timebase settings so you can see the details on your signals.
See your signals more clearly
The DSO1000A Series incorporates a bright, crisp LCD color display. You can quickly view your signal from almost any angle. Unlike conventional scopes that always require menus to be on, the entire 5.7-inch diagonal screen is available for waveform display as needed.
True Zoom mode for signal details and context
Dual display and True Zoom shows your entire signal and zoomed in waveform details at the same time.
23 automatic measurements
All DSO1000 Series scopes come equipped with 23 automatic voltage, time and frequency measurements. Press the Measure key to bring up the three you use most often or display all single-channel measurements on the screen simultaneously.
Sequence mode for easier debug
Record up to 1000 occurrences of a trigger event and then play them back to easily spot glitches or other anomalies for further examination. Store the waveforms to internal or external memory (USB flash drive).
Digital filtering on waveforms
Apply a real-time digital filter of your choice to the source waveform to eliminate unwanted frequencies from your display. Digital filtering selections include low-pass, high-pass, bandpass and band-reject filters. Frequency limits are selectable between 250 Hz and the full bandwidth of your oscilloscope.
Advanced triggering
Triggering options for the DSO1000A Series include edge, pulse width, composite video, pattern and alternate channel trigger modes. These modes ensure that you can capture and view hard-to find signal conditions.
Make fast go/no-go decisions
Automatic pass/fail mask testing comes as a standard feature on all 1000 Series scopes. Acquire a "golden" waveform and define tolerance limits to create a test envelope. Incoming signals will be compared to the allowable range and quickly flagged as pass or fail. This is ideal for manufacturing or service where you need to make decisions quickly.
Waveform math and FFT
Standard math functions include addition, subtraction or multiplication of any two input channels and Fast Fourier Transform (FFT) with four user-selectable windows (Rectangle, Hanning, Hamming and Blackman).
Programming and Connectivity
For remote instrument control over USB, use Agilent's I/O library or National Instrument drivers in your application. The drivers are compatible with Agilent VEE Pro, National Instrument's LabView and LabWindows/CVI.
Built-in USB host and device ports and free IntuiLink software make documentation and PC connectivity easy. Store waveforms and setups to a USB flash drive, easily update scope firmware and print to any PictBridge compatible printer.

Here is a flash movie, pretty self explanatory:

Personal, I like the Zoom function, the Sequence and the Save/Recall.

The signal generator is a ZOPAN KZ1405 Function Generator  produced in the 80's by the Polish Institute and Scientific Equipment Manufacturing -Zopan.
It covers 0,01 Hz - 10 MHz in square, triangle and sinus waveform. It's a well built analogic signal generator and it works very nice. Only a little contact spray to the potentiometers...
Has sinusoidal, triangle and square wave forms, all of them with variable ratio (they call it "symmetry") and a very usefull offset setting!

Very, but very simple and reliable!
I will change the capacitors when I will have some time because I suspect that some distorsion at 0-10 MHz due to ageing.

Some guys thinks the KZ's are adequate for making music... Well, I don't!

Multifunction Generators Zopan type KZ 1046 0.0005 Hz-100 kHz from zopan records on Vimeo.

Thanks to a great Polish guy, I do have the schematics for my Function generator!  Niiiiiceeeeee!

18 iulie 2014

Digital Multimeters

I wrote about receiving the VC-1008, the new multimeter in my shack.
Well, I told you that I have a very old DMM, a Voltcraft VC98 with 3 and 1/2 digits.
I bought it from my first wage, back in 1995 and was around 200 USD at that time. A lot of money!
I never succeded in my trial to make him communicate with my PC via IR...
It has no autorange, the selector is a pain in the a&*^&* but it works! Yes, it works perfect and even has a bargraph wich is very nice. It's a backup DMM in my shack.

The other one is also a Voltcraft, a VC-960, top of the DMM in 2011 if I remember right... Have some issues with it but manage to make it back in service. At least at 90% (still have some problems with AC current measurements).

Here are some pictures:

The VC-98 near the VC-960:

Voltcraft VC-960:
 Voltcraft VC-98:

 Schematic diagram of the Voltcraft VC-960:

10 iulie 2014


Well, "Greed Deep-meter" is not  tthe correct form!
"Greedometer" or "Greed-o-meter" seems more appropriate to me.

Greedy hams!

A new multimeter in the shack.

Since 1996 I am a fan of Voltcraft multimeters. The first one was a VC98. It still work altough is heavy modified to overpass the years. It is not very precise and has a little problem with the rotary selector but still in service.

The second one is younger but I managed to fry it a little. It is a VC 960. I love it, especially for the 200 Mhz f-meter and the 5 digit measurement capability. Not in production anymore and I couldn't find one from a good seller.

So, I ordered from Conrad a VC1008. 

First impression is positive. It already has the external power connector and it works with 4 AA batteries that can be rechargeable ones.

The case feels a little cheaper than the VC960 and the max. freq. is only 8 MHz.

Another positive is that the optical USB interface and the software are included. For the VC960 I had to purchase the optional interface.

I found the schematic for my VC960 and I will try to make it work again.
Happy Birthday to Me!
posted from Bloggeroid

05 iulie 2014

Extreme unpolite station...

While I was trying to call a station from Mauritius, an Italian station started the transmission below:

3:02:57 PM> Main
pse kn

*** Hello my friend YO3HJV/P COPY  IK1LRY IK1LRY
 Rst(Q):.599 599 s/n  9 dB/ imd -28 dB
 MY Name:.IS Francesco Francesco
Qth :. Moretta nr Torino
Y:.(65)  LIC :.(1988) LOC:.(JN34SS [279.3° 1,442.8km])
My:.qsl only via www.e.qsl.cc Automatic (AC)
Good luck 73 your family.t.n.x for qso bpsk31  khz  21Ø7Ø.577
how dow copy de  IK1LRY (YO3HJV/P) ciao bye sk <(*/_*)>

3:04:46 PM> Main
ik1lry pse qrx
pse kn
pse kn

Of course, 3B8FA wasn't on air when the italian station finished the unwanted QSO.
No, I do not logged that!

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