audio recording on IC -help wanted

[Winfield Hill]

Chris Jones wrote...

Winfield Hill wrote:
Jeff wrote...

Needs to drive into 50 ohms. input level approx 150mV at 5Mhz

Winfield Hill wrote ...
Jeff wrote...

Ive been trying to locate a suitable unity gain buffer amplifier
IC that can drive a 50 load. Application is to buffer a VCO
output at 5Mhz. Needs to be 8pin DIP

LTC's LT1206 comes in TO220, miniDIP and soic packages,

and operate on a single-ended supply.

Oops, +/-5V supply. What's your signal voltage? And did
you want your output to have a 50-ohm source impedance?

Unless you source with 50 ohms (2x signal plus 50-ohm resistor),
and terminate with 50-ohms, the issue becomes how much cable
capacitance? Either the load looks resistive (100 ohms in the
former case) or capacitive.

I would say it depends on the cable you choose. If there is a 50 Ohm
load and you connect it to your buffer amplifier with 50 Ohm coaxial
cable, then the buffer amplifier will see a 50 Ohm resistive load,
not capacitive at all.

It is probably still wise to use the gain-of-two amplifier and 50 Ohm
source resistor in case the load happens to be a poor match. If you
really don't need this feature then I would be tempted to use an
emitter follower with just one transistor. (Do they make transistors
in DIP-8 packages?)

I agree, if the load has no capacitance, source terminating with
50-ohms eliminates the cable-capacitance issue, and the driver only
sees a 100-ohm load at high frequencies, above those where the open-
end reflection has time to return. Although the input to the cable
is attenuated by 2x (hence the 2x gain you suggested), the end of
the cable gets the 2x back due to the open circuit, so a gain-of-two
amplifier shouldn't be needed. Just the 50-ohm sourcing resistor,
after the emitter follower.


--
Thanks,
- Win

 

[Chris Jones]

Winfield Hill wrote:

Chris Jones wrote...
Winfield Hill wrote:
Jeff wrote...

Needs to drive into 50 ohms. input level approx 150mV at 5Mhz

Winfield Hill wrote ...
Jeff wrote...

Ive been trying to locate a suitable unity gain buffer amplifier
IC that can drive a 50 load. Application is to buffer a VCO
output at 5Mhz. Needs to be 8pin DIP

LTC's LT1206 comes in TO220, miniDIP and soic packages,

and operate on a single-ended supply.

Oops, +/-5V supply. What's your signal voltage? And did
you want your output to have a 50-ohm source impedance?

Unless you source with 50 ohms (2x signal plus 50-ohm resistor),
and terminate with 50-ohms, the issue becomes how much cable
capacitance? Either the load looks resistive (100 ohms in the
former case) or capacitive.

I would say it depends on the cable you choose. If there is a 50 Ohm
load and you connect it to your buffer amplifier with 50 Ohm coaxial
cable, then the buffer amplifier will see a 50 Ohm resistive load,
not capacitive at all.

It is probably still wise to use the gain-of-two amplifier and 50 Ohm
source resistor in case the load happens to be a poor match. If you
really don't need this feature then I would be tempted to use an
emitter follower with just one transistor. (Do they make transistors
in DIP-8 packages?)

I agree, if the load has no capacitance, source terminating with
50-ohms eliminates the cable-capacitance issue, and the driver only
sees a 100-ohm load at high frequencies, above those where the open-
end reflection has time to return. Although the input to the cable
is attenuated by 2x (hence the 2x gain you suggested), the end of
the cable gets the 2x back due to the open circuit, so a gain-of-two
amplifier shouldn't be needed. Just the 50-ohm sourcing resistor,
after the emitter follower.

What I meant to say is that there is no need for a resistor at the amplifier
end of the cable, provided we know for certain that the load is resistive
and of the right impedance to terminate the cable, i.e. accurately 50 Ohms.
If this is the case, then there is no need for an amplifier with voltage
gain, which might make thing easier. If the load is not close to 50 Ohms
and if we care about the frequency response, then terminating both ends of
the cable makes a lot of sense.

There is a more important question which the OP could answer which is: what
is this whole thing for? Is the VCO incapable of providing enough current
to drive the cable, or is the amplifier there to provide reverse isolation
so that the load cannot affect the frequency, or is there another reason
why we need this buffer amplifier? Anyway at 5MHz I would probably try to
do it with one or two transistors rather than buying a chip, since the
continued availability of transistors is more likely.

Chris

 

[buran]

The TDA8362 is the SECAM version of the PAL TDA8361.

I.

 

[Mike Harrison]

On 13 Oct 2005 07:47:08 -0700, surjones@yahoo.com wrote:

I'm pretty new to thermal sensing and such, but I have a friend who
wishes me to make/aquire 3 types of temperature sensors, all with
greater than .1 degree celsius accuracy.

1) Ambient temperature
2) Contact temperature
3) Radiation temperature (a "directional" sensor of sorts which detects
IR radiation coming from a source). A further requirement is that if
this sensor (or array of sensors) can tell me the temperature /amount
of radiation in each Thermal IR band within 8.125 to 11.60 Micrometers
(total 5 bands within this bandwidth)(This should preferable correspond
to a satellite sensor band seperation, as he is doing some urban heat
phenomenon research).

I've done some experiments with NTC Thermistors before-I did some
interfacing to the PC joystick port. I thought maybe I can use the same
NTC thermistor for the above uses? Is the thermistor meant for "such"
sensitive work? (If I uses a better ADC)..and can I modify it in some
way to measure the radition temperature as well? (by adding some sort
of parabola?!)

It would be best if I can get cheap sensor(s) which I can interface
myself (to the PC), but worst comes I can buy one/seperate standalone
devices which preferable have some sort of computer connectivity and
some memory.

Many thanks
Suraj

If you really need 0.1 deg accuracy (as opposed to resolution), then PT100 sensors are pretty much
your only sensible choice.
I think this accuracy in non-contact would be extremely difficult if not impossible - certainly
extremely expensive if it is do-able.

 

[Mike Harrison]

If commiting to PT100 solution, you need precision constant current
source involving precision voltage reference (which interface to op-amp
that provides regulated current output). Some care on circuit is
needed.

No you don't. All you need is an accurate & thermally stable reference resistor in series with the
PT100 excitation current - you use the voltage across this resistor as your ADC reference, so you
are making a direct measurement of resistance of the PT100 - the current cancels out (within
reason).

The only requirement on the current source is low noise and low short-term drift.
Many delta-sigma ADCs have differential reference inputs which are ideal for this sort of
application.

 

[Tim Wescott]

redbelly wrote:

surjones@yahoo.com wrote:


Just curious, But I remember reading that CCDs have similar response to
IR as to light.. is this so? if so, can there be this remote
possibility that I turn a 5 Mega pixel Digital camera as a thermal
imager of sorts? maybe with appropriate "IR filters" ?


A silicon CCD measures infrared only up to 1.1 um, not suitable for
thermal detection at room temperatures.

By the way, here is a product that claims a 0.1 C sensitivity:

http://www.infraredcomponents.com/uncooledmodules.html

However, you will not get that 0.1 C accuracy if you don't know the
emissivities of the different objects you'll be measuring.


Also, Can I ever use IR diodes (like those in a TV) for any kind of
temperature measurement?
Many thanks
Suraj


Probably not for you, they'd just work for high temperature
measurements. I'm not sure if these diodes are silicon (good up to 1.1
um) or something else, but it's a pretty sure bet they are NOT
sensitive at 8-11 um. (Perhaps somebody else in here knows better?) A
silicon photodiode might be sensitive at 250-300 C and higher
temperatures, but that number is something of a guess on my part.

Mark

You can do pretty good radiometry at 3-5um, at least if you're working

above freezing. I used to work for FLIR systems, going back to when the
Portland operation made handheld cameras with PtSi cooled sensors.
These days it's all done with microbolometer arrays at 8-12um.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[William P. N. Smith]

surjones@yahoo.com wrote:

Lets say I want As much accuracy as possible with a *decently low cost
solution* (200 $ ?)

http://www.campbellsci.com/107-l has a:
/*
Polynomial linearization accuracy:

* <ą0.5°C (-35° to +50°C)
* <ą0.1°C (-24° to +48°C)
*/

and costs about $70, but I suspect the details are in the (multipoint)
calibration and the interface electronics.

I think you really need to follow other responder's advice and rethink
what you mean by "0.1 degree" accuracy. First of all, it's
essentially meaningless in the real-world, and secondly it's pretty
much impossible to get with your budget.

WHY do you want such accuracy, anyway? Just because your friend sent
you off on a wild goose chase?

 

[William P. N. Smith]

surjones@yahoo.com wrote:

This is getting, confusing, complex and interesting!

Not to mention silly.

I mean this friend person just wants to go outdoors (with the sun
shining and all) and go to a spot (a longitude/latitude that he
identified from his satellite thermal IR image) and take/sample the
temeperature there. and then he wishes to relate the satellite thermal
imagery with the on-ground samples that he thus takes

He wants to confirm satellite thermal IR images with real temperature
measurements to within 0.1 degrees C?

Words fail me.

 

[Ray L. Volts]

"Bill" <fred_barney@bigmailbox.net> wrote in message
news:lvudnahU0qxN3-beRVn-iQ@dejazzd.com...

Does anyone out there have an MSM5205 OKI speech chip I might buy. I am
trying to repair an old Data East Pinball machine that has a bad sound
board
and it looks to be the voice chip. It appears that this chip is extremely
obsolete and the only way I can get a hold of one is by buying a minimum
of
8 pieces for 30 some bucks a piece. In lieu of the 5205 how about a
MSM6585, it appears to be a drop in replacement for the 5205. I really
need
some help on this as I have 3 little girls who keep asking when 'daddy's
game' is going to be fixed so they can bounce the balls around again.

Thanks

Bill
email: myemail@pflum.com

http://www.findchips.com/avail

shows two stocking sources.. dunno bout min. qty or prices, though.. good
luck

 

[Mike Harrison]

On 17 Nov 2005 04:44:30 -0800, "lawlopez" <lopez@mv.mv.com> wrote:

1. Relays generally eplloy air or vacuum so they can hardly be called
solid state.

2. If you use a discharge device you will need to commutate it or turn
it off.
This is often done by using a second device and a capacitor in power
control circuits.
Anther way which is often used in pulse radar sets is to use resonate
the output
capacitor.

Personally I'd use a trigered spark gap, but that's just me.

Another realistic possibility is to take a lower voltage pulse (say 500
volts) and just step it up to 10KV. This makes the parts on the
primary at a more tractable voltage level.
with a transformer.

You could maybe used a marx-generator type topology, using mosfets instead of sparkgaps for the
switches.

 

[William P.N. Smith]

Jim Thompson <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

I've used a light bulb in series with a rectifier to charge a car
battery (just make sure that line ground goes to chassis ground ;-)

Anyone else remember the Radio Shack dry battery chargers based on a
7W night-light, a rectifier, and a flexible battery holder? The light
is an (aproximately) constant current source...

 

[Oliver Betz]

"Günther Dietrich" <guenther_dietrich@despammed.com> wrote:

http://en.wikipedia.org/wiki/Labskaus

Uh, real Labskaus doesn't contain fish. And the picture is
unappetizing.

During my time in the german military, I had some courses of instruction
on a base near Hamburg. One day they served Labskaus in the staff
canteen there. That stuff looked just like that on the wiki photo.

Well, then the cook is to blame, not Labskaus per se. Go to Hamburg
and visit the "Old Commercial Room". I guess they make still delicious
Labskaus.

Oliver
--
Oliver Betz, Muenchen (oliverbetz.de)

 

[es]

"PrecisionMachinisT" <precisionmachinist@hotmail.com> wrote in message
news:h_adnfqAaLsmkwzeRVn-jQ@scnresearch.com...

"Charlie Gary" <cgary@modelwerks.com> wrote in message
news:1133569000.015187.146500@g47g2000cwa.googlegroups.com...

es wrote:
..Well, I figured such a simple plane could be CNC'd with a hot wire or
even
routered.
Wondered if anybody here is/ has done this kind of activity
with
success .

Sorry I forgot to mention that part, but thank-you for the opening
opportunity to lead into it !

hot wire? CNC? EPS? A knee mill, vary-ac and some safety wire will
get you going.


Hi, Charlie

Pretty sure you had meant to say " variac " above....

FWIW, these probly pop up routinely on ebay.


SVL

Or maybe he meant variable Resistor or variable AC (in this case it
doeesnt matter much wether u pump AC or DC into the hot wire as either
current source will create the heat from electron flow/collision in the
piano-type (nichrome) wire )

http://www.amptone.com/tenmavariac.htm (a variac which has a potentiometer)

http://cgi.ebay.com/NEW-2K-VA-VARIABLE-TRANSFORMER-VARIAC-2000VA-0-150V_W0QQitemZ7567118929QQcategoryZ1504QQtcZphotoQQrdZ1QQcmdZViewItem
Actually I think it's a variable transformer. Maybe we can cross post to
sci.electronic.components to get the real answer

 

[William P.N. Smith]

"jeffrey" <johjeffrey@hotmail.com> wrote:

I want to build a alarm clock that will start counting up when it is
triggered. (e.g., at 5AM, it will go off and start counting 1 second,
2 second.) I can't seem to be able to find clocks like these. (I know
there are timers that will start counting up, but not clocks)

I'm pretty sure the clocks at http://countdownclock.com/ will start
counting up after they hit their target. I've got a Y2K clock from
them kicking around somewhere, and I seem to remember this behavior.
Check with them to be sure...

They start at $13 for the blank "make your own" clocks...

 

[William P.N. Smith]

"Christopher Ott" <chrisott *at* ottelectronics *dot* com> wrote:

Any elegant ideas to protect a normal opamp while keeping the parts count
low?

Current limiting resistors and schottky diodes to the positive supply?

 

[CWatters]

"default" wrote in message
news:s64sp19iqbrr1j5vg05b57qlot79sg8oo0@4ax.com...

Add a clamping diode from the input to the positive supply rail of the
op amp, and add a small resistor on the input signal to keep it from
frying the diode (assuming there isn't already one there for the
circuitry)

That sort of problem could be designed out.

and might eliminate need for a fancy ESD protection device as well.

 

[William P.N. Smith]

"jeffrey" <johjeffrey@hotmail.com> wrote:

Thanks. I asked the guy at Radio Shack, and he said that the hardest
part would be finding the relay switch in the alarm clock. How can I
find that?

You don't have to, just rectify the speaker output and use it to
trigger your stopwatch.

 

[William P.N. Smith]

kellrobinson@billburg.com wrote:

I need a series of led's (about 7) to use as a voltage reference.

How about a bar-graph display, and just wiring the elements in series?

 

[William P.N. Smith]

"kell" <kellrobinson@billburg.com> wrote:

kellrobinson@billburg.com wrote:
I need a series of led's (about 7) to use as a voltage reference. I
want to use led's because I need a certain tempco and using a series of
led's for the voltage reference will give me the right tempco.

And once again you haven't bothered to mention _why_ you want a
particular tempco, what it is, or even what voltage you want (7 LEDs
could be anywhere from under 12 to over 20 volts). The answers you
get are only going to be guesses based on hte information you bother
to divulge.

 

[William P.N. Smith]

"Ken" <lerameur@sdom.com> wrote:

Output Transformer
900 8
----- -------
-
-----
-
----- ---------
Three legs going in and two out with these numbers on top.

Looks like a speaker output transformer, 900 ohm (center-tapped)
primary and 8 ohm secondary.

Radio Shack used to carry this kind of thing, but you probably have to
try digikey.com for it nowadays.