Driver to drive?

[Leon Heller]

"Dummy" <ahkit1021@yahoo.com> wrote in message
news:74bb84c0.0411021808.24369694@posting.google.com...

There are two VHF (136-174MHz) radios and two UHF (438-470MHz) radios.
For UHF radios, some kind of noise appeared at receiver radio's
speaker when key chain is jingled at the transmitting radio. This
happened even when the microphone was disabled/unplugged from the
transmitting radio. I don't see any way that the noise could be
coupled to the microphone. The noise amplitude (as audible) was much
more lower when antenna was detached. What actually happened there? No
such peculiar phenomena was been observed in VHF radios though. I
suppose it's the interaction between the key chain and RF radiation
field, and caused VCO pulling?

Perhaps there is a microphonic capacitor in the Tx. Many ceramic capacitors
are microphonic.

Leon

 

[xray]

On Wed, 03 Nov 2004 03:54:34 GMT, Scott Stephens <scottxs@comcast.net>
wrote:

Anyway how is my mind not open?

Dude. You are scaring me. May the real spirit encompass you.
Stop buying into false prophets and look for the real meaning.
Everything in the bible should not be taken literally.

I think during their lifetimes all the religious leaders had pretty much
the same message. Now we are dealing with hundreds or thousands of years
of interpretation.

 

[xray]

On Wed, 03 Nov 2004 03:54:34 GMT, Scott Stephens <scottxs@comcast.net>
wrote:

Anyway how is my mind not open?

I just read some of your other posts in a different context.

Maybe I misjudged you after reading only a few paragragraphs.
If so, my apologies.

 

[Paul Burke]

Spehro Pefhany wrote:

Okay. Why 0805s? I'd suggest 0603 or even 0402 where there's a choice.


0805s make for easier visual testing (whether you test all or just

sample) as the resistor values are written in plain- this is not so with
many 0603s and below.

Paul Burke

 

[Robert Baer]

Paul Burke wrote:

Spehro Pefhany wrote:

Okay. Why 0805s? I'd suggest 0603 or even 0402 where there's a choice.


0805s make for easier visual testing (whether you test all or just
sample) as the resistor values are written in plain- this is not so with
many 0603s and below.

Paul Burke

Furthermore, more values (in cut tape and reels) are readily
available.

 

[Anders F]

"Joel Kolstad" <JKolstad71HatesSpam@Yahoo.Com> wrote in message

Interesting... at Tek they spend a LOT of time (literally man-months,
maybe
even years!) worrying about things like menu layout. This might be a case
of where 'design by committee' ends up being less user-friendly than if
just
one or a few engineers had gotten together to do the design.

I find that kind of hard to believe! Not that I think the menus are bad -
'cause they are not. But my TDS3032 have definitely not been tested by real
people. The lag when pushing the rubbery (with poor tactile feedback)
buttons is unbearable. Every time I haven't used it for a while I keep
pressing them twice.
Besides that it's a great scope!

/Anders

PS: I /think/ they fixed it in the B versions...
PPS: The FFT key is also vastly expensive (FFT is not that hard to do is it
;-) - one actually thinks about hacking it ;-)

 

[Don Pearce]

On 3 Nov 2004 01:10:45 -0800, cv97035@central.ntua.gr (Alex Markatis)
wrote:

Hi everybody!

I have been planning to make a laser distance measurement device for
using at work (I am a civil engineer). Could anyone inform me where I
can find a laser device for that purpose on the Internet? I don't need
a display or a box, just the laser. I would also like the laser to
have a serial port for communication. I am interested in distances up
to 50m aprox.

I 've been doing some googling, but all I can find is complete devices
ready for use, which don't quite fit to my needs.

Thank you very much in advance!


Google for laser diode and you will find plenty of bare components.

d
Pearce Consulting
http://www.pearce.uk.com

 

[Anders F]

"Alex Markatis" <cv97035@central.ntua.gr> wrote in message
news:86eeb5ef.0411030110.36f43c41@posting.google.com...

Hi everybody!

I have been planning to make a laser distance measurement device for
using at work (I am a civil engineer).

Hmm - sounds like a very difficult project! I don't know how they actually
work - but I'd guess they're measuring phase differences on the reflection?
Takes very precise reference clock and high-speed electronics. Speed of
light is rater fast - why all the cheap distance meters use ultra sound...

Could anyone inform me where I
can find a laser device for that purpose on the Internet? I don't need
a display or a box, just the laser.

....so my guess is you'll actually want an expensive finished unit? Not just
a laser!

/A

I would also like the laser to
have a serial port for communication. I am interested in distances up
to 50m aprox.

I 've been doing some googling, but all I can find is complete devices
ready for use, which don't quite fit to my needs.

Thank you very much in advance!


Alex Markatis
Civil Engineer
National Technical University of Athens
GREECE - HELLAS

 

[Gareth Magennis]

It's also worth noting that the ones I use have the back conducting surface
exposed, so you need to cover it with insulating tape or laminate the whole
thing.

Sharp shears will cut them with little problem, but always measure to
assure a
clean separation between the elements.

Good advice from Clarence - I've made a couple that were short circuit.

The voltage for most phosphors is about 85 to 135 Volts AC at about 400 to
800
hertz. They will work on 60 hertz at a reduced output.

 

[legg]

On 2 Nov 2004 10:46:32 -0800, david.pariseau@sbcglobal.net (David
Pariseau) wrote:

The problem was actually a voltage spike on startup (switching on the
Variac) that was large enough (>9000v) to toast the reference. I
guess it makes sense that the auto-transformer might have such an
excursion initially with such light load.

I added a 10K resistor in series with my 450K resistor and added a TVS
from this new node to ground and voila...

How'd you catch/measure this 9KV pulse?

RL

 

[Paul Burridge]

On 3 Nov 2004 06:08:32 -0800, Winfield Hill
<whill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

I need a few 40W 40MHz RF power amplifiers and can think of a
half-dozen ways to do it, from RF transistors to commercial
modules, but I'm not that happy with any of my ideas; there
has to be something better out there. The load is tuned, but
I'd like a Q of no more than 40. Suggestions for easy-to-get
transistors or modules, etc.?

That's a radio control frequency (here in the UK at any rate) with a
Po limit of 100mW! Are we near sunspot maxima? If so, kindly drop me
an warning e-mail if you're planning on using that thing!
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[legg]

On Tue, 02 Nov 2004 22:39:39 GMT, "Norm Dresner" <ndrez@att.net>
wrote:

The highly recommended book Art of Electronics (by you know who) makes
liberal use in sample circuits of current regulating diodes in he
1N5283-1N5314 series. And to me they make a lot of sense in terms of
reducing parts count. I just looked for one to build one of the circuits
and found that DigiKey has none and Mouser wants $4.29 for a single 1N5297!
That's simply outrageous.

I could use an LM334 Adjustable Current Source -- that's only $0.75 + one
resistor but more board space.

Of course there's always a discrete FET and a trimmer -- or a BJT +
resistors. All of which are more complex, more error prone, and more likely
to fail.

Am I missing anything?

Were the Current Regulating Diodes simply a good idea that never made it in
the marketplace?

They were never cheap enough to use in production. Most mfrs, when
pushed, would just select their own fets for idss, or use a fet and a
resistor.

RL

 

[Paul Burridge]

On Wed, 03 Nov 2004 01:26:49 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Hi Paul,

I'm sure you appreciate I have not the slightest ill-will against your
only-to-be-expected views. But you may wish to take into account that I have
just consumed a bottle of cheap plonk - a claret.



In vino veritas, Reg; in vino veritas.


So what is cheap plonk? The category "mise en bouteille dans notre garage"?

Shouldn't that be *une* bouteille? ;-)
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Paul Burridge]

On Wed, 03 Nov 2004 02:13:30 GMT, Rich Grise <rich@example.net> wrote:

Get a meter and a soldering iron and some parts and a proto-board or
one of those 101-in-1 kits, and read a lot.

Thanks for the encouragement, Rich, but I did all that in the late
60's! I'm convinced it's a problem with the way I look at things. I
often overlook the obvious, simple solutions and see things as far
more complicated than they are. Occasionally, of course, they *are*
actually more complicated than they seem. But I can't tell which is
which!
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Paul Burke]

Robert Baer wrote:

0805s make for easier visual testing (whether you test all or just
sample) as the resistor values are written in plain- this is not so with
many 0603s and below.


Furthermore, more values (in cut tape and reels) are readily
available.

Funnily enough, Farnell UK sell the whole E192 range in 0603 but NOT
0805, and in both small quantities and reels.

Paul Burke

 

[Paul Burke]

Alex Markatis wrote:

I have been planning to make a laser distance measurement device for
using at work (I am a civil engineer). Could anyone inform me where I
can find a laser device for that purpose on the Internet? I don't need
a display or a box, just the laser. I would also like the laser to
have a serial port for communication. I am interested in distances up
to 50m aprox.

If it has RS232 comms, it IS a "box", as a laser is just a light
effectively. It's like asking for a 60W bulb with Ethernet.

One principle I know of is to modulate the laser beam and measure the
phase difference with the reflection. A cube- corner prism is used to
ensure the beam goes back to the device, and not somewhere else. Since
the phase difference repeats, phase is measured at a number of
modulating frequencies.

I like the way the modern total stations automatically follow the guy
with the pole about- how do they do that one? He's not always pointing
the prism in the right direction IIRC.

If this discourages you, look up Leica Disto.

Paul Burke

 

[Markus Mandl]

Alex Markatis schrieb:

Hi everybody!

I have been planning to make a laser distance measurement device for
using at work (I am a civil engineer). Could anyone inform me where I
can find a laser device for that purpose on the Internet? I don't need
a display or a box, just the laser. I would also like the laser to
have a serial port for communication. I am interested in distances up
to 50m aprox.

I 've been doing some googling, but all I can find is complete devices
ready for use, which don't quite fit to my needs.

Thank you very much in advance!


Alex Markatis
Civil Engineer
National Technical University of Athens
GREECE - HELLAS

Laser + RS232 + 50m = Leica Disto

Regards
Markus

 

[ChrisGibboGibson]

We've just completed beta testing of a PCB that's going into production at this
moment in time.

Components are:-

1 X 18 pin IC
1 X 16 pin IC
5 general purpose trannies
21 X Rs
8 X Cs (non-polarised)
4 X 7 seg LED display
2 X push buttons
2 X polarised caps.
1 X ICSP connector (we went for edge connector as it's essentially free)
1 X 5 way screw terminal

In quantities of 100 manufacture PTH was 56% more expensive than SMD. This is
manufactured in the UK

Main cost differences were:-

Less holes in PCB for SMT
SMT components cheaper.
SMT, less manual labour.
Initial set up costs slightly higher for SMT.
No silk screen on SMT (rather pointless)

One big difference was made by managing to get all the components on one side,
this means the SMT could be flow soldered, then the PTH components inserted and
wave soldered. If this had not been possible then the PTH would have to be hand
soldered.

Gibbo

 

[Anders F]

"Markus Mandl" <Mandl-Bayreuth@t-online.de> wrote in message

Laser + RS232 + 50m = Leica Disto

Could the curious ones of us maybe have a price indication?

Cheers,
Anders

 

[Markus Mandl]

Anders F schrieb:

"Markus Mandl" <Mandl-Bayreuth@t-online.de> wrote in message

Laser + RS232 + 50m = Leica Disto


Could the curious ones of us maybe have a price indication?

Cheers,
Anders

If think they were about 500 to 1500 USD - depending on the model.
You could also check eBay for used ones.

Regards
Markus