[time-nuts] Re: Crystal oscillator for a begginer

[Hal Murray]

> Things like soldering and PCB are things I've heard of...

Soldering is pretty basic to low level electronics.

If you want to learn soldering, you might see if any of your neighbors can 
help or if your local community college has a class that fits.  Or the local 
ham radio club...  Or the local Maker Fair...  There is a lot of stuff is that 
is easier to learn if you can see it and get immediate feedback from somebody 
watching what you are doing.

This is the background I would give to a friend if he asked me something like 
your question.

To get started, you need basic tools: screwdrivers, pliers, wire stripper...  
(and a toolbox)  If nothing else, you need to be able to take the cover off a 
box to see what is inside it.  That's both to admire good work and to check 
for smoke or corrosion.

Next on the list would be a handheld meter.  Often called VOM for 
volt-ohm-meter because the typical package reads volts and ohms and usually 
current.  Prices are $5 to over $100.  You probably get rougly what you pay 
for.  Well known brands are on the expensive end but you can be sure of what 
you will get.

For soldering, you want an temperature controled iron.  If your eyes are as 
old as mine, you need good lighting and a magnifying setup.

For general electronics, I'd say an oscilliscope is the most useful piece of 
lab gear.  Ballpark price is $200-$500.  Fancy ones cost as much as a car.  
The probes are important (and expensive).  If you are focusing on time-nut 
things, you can probably get by without one.

For time-nut work, the most important lab gear is a counter/timer.  They 
typically have 2 inputs and run in either of 2 modes.  In frequency mode, they 
count the number of cycles on an input signal for 1 second, or 0.1 second or 
..., do the arithmetic, then display the answer as the frequency of the input 
signal.  In timer mode, they count the number of cycles of an internal clock 
between a start signal and a stop signal and display the answer as a time.  
That can be a pulse width, or the time between pulses, or the time offset 
between 2 signals.

Timers usually have an option to use an external reference.  Their cost often 
depends on the quality of the internal reference.

There are lots of older HP timers on eBay.  (Some models have displays that 
get old.)

----------

Most timers (and digital scopes) have a USB or HPIB/GPIB connector so you can 
collect data for things like ADEV plots.  GPIB needs a GPIB to USG gizmo or a 
card for your PC and cable.

Timers (and digital scopes) have an internal oscillator.  You can reverse 
things: feed them a known good (accurate) signal and see what they say.  If 
they say your 10 MHz signal is 10.001 MHz, you know the internal osc is 
running at 9.999 MHz.

---------

In the time-nut area, a good reference clock is handy/important.  The typical 
way to get one is with a GPSDO.  Old standbys are HP Z3801A and Trimble 
Thunderbolt which were available surplus.

eBay shows lots of hits to GPSDO.  I'm not familiar with any of the newer 
ones.  Check the archives.

You may want/need a good external antenna.

---------

There is some modern scope and timer gear without any knobs or display.  They 
connect via USB and let the PC do most of the work.  They are much less 
expensive.  I haven't used the scope versions other than a quick demo by a 
friend.  It looked very good on a big PC display.

The TAPR TICC is a USB timer.  You provide a 10 MHz reference clock.  It gives 
you time stamps for 2 input signals.  If you want to measure frequency, you 
need something like a PIC front end to divide the input signal down to a PPS.

There is a PIC time stamper - one channel.  You could make a multichannel 
version with multiple PICs.  You would have to setup a reset signal going to 
all of them, or feed them the same signal and calibrate the offsets.

---------

You can learn a lot by reading the manuals for gear and data sheets for chips.

The Z3801A manual is good.

--------

If you want to build things without soldering, there are solderless 
breadboards.  You need to supply power.  This one has a power board.  You 
supply power from USB or a wall wart.
  https://www.ebay.com/itm/203505707452
There are lots of similar setups.  I don't see any documentation.

You can't see it unless you know what to look for...  The holes are on 0.1 
inch centers, often used by chips.  You put your chip in the middle with 1 set 
of legs in holes on either side of the center line.  The row of 5 holes 
starting with a leg of your chip are connected underneath so you can easily 
get up to 4 connections to each pin.

One of those could easily hold the oscillator from your first message and a 
PIC to divide it down to 1 MHz.

--------

On PCBs (and soldering).

There are several steps in designing/using a board:
  You need to design the circuit.
  You need to layout the board: chip goes here, wire goes there, mounting holes
  You need to build the board itself.
  You need to assemble the parts on the board.

If you have the layout, you can send it off to mail order places that will 
send you back boards.

Assembly requires soldering.  That is easy to hard depending on your skill and 
if the board uses parts with tiny pins or only ones with big pins.  Big means 
0.1 inch centers, old DIPs.  Most people can work with that.

---------

Odds and ends:

If your wires get longer than a foot, you need to understand transmission 
lines and reflections.

---------

Books:

The Art of Electronics by Horrowitz and Hill is a classic.  Big, heavy, 
expensive.  It's weak on computing and hacking with things like PICs but great 
on analog.  See if your library has a copy that you can browse.  The 3rd 
edition came out a few years ago.

---------

If you want a starter project...

I would suggest your 10 MHz osc and a PIC to divide that down to a PPS on a 
solderless breadboard.   Feed that to a GPIO pin on your Pi.  Setup that pin 
to capture PPS.  Write some code to collect data.  You should be able to 
measure the frequency and watch it change with temperature and maybe aging.


-- 
These are my opinions.  I hate spam.