Searching \ for '[OT]: Simple questions...' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=simple+questions
Search entire site for: 'Simple questions...'.

Exact match. Not showing close matches.
PICList Thread
'[OT]: Simple questions...'
2003\11\10@174456 by Tim Hart

flavicon
face
HI all...I have a few quick simple questions for the group...

I have a transformer with 4 leads on the AC side and 6 on the output side.  I'm a bit confused...I'm used to 2 on the input side and 3 on the output.  Any idea how to even test the transformer?  I tried measuring the ohms....they are all very close....

Another transformer I have is 110 to 16 volt...I hooked it up backward to see if I could get a few hundred volts AC...nope...it popped my circuit breaker....why did it not act as a step up?  Do I need to limit the current I feed it?

And hearing Ultrasonic.  I want to audibly hear the output of a ultrasonic transmitter....can I build an amp that shifts the frequence down to a level I can hear via a speaker?  Any ideas?

Thanks for hearing me out...I know these are newbie questions....

Thanks,
Tim

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\11\10@181746 by Rick C.

flavicon
face
I'll try to answer some of your questions.

1) Some transformers have two primaries. This allows hooking them up in series for 240 volt operation. You must have them wired "in phase" or it will overheat the transformer and damage it. Sometimes there is a color code, sometimes numbers. Sometimes you
can find a datasheet online or from the vendor. You can also test it "trial and error" with a 25 watt light bulb. **Be careful with dangerous voltages*** With an ohmeter, pair off the two primaries. Parallel the inputs and put the bulb in series as if it
were a fuse. If it lights bright, its hooked up wrong. Reverse one set of windings and the light should not light. Check for proper output voltage on the secondary. You now have it wired in phase. Depending on your current demand you may get away with
using just one primary, but the efficiency is somewhat reduced.
There is also the chance that there is only one primary with taps for different mains voltages. i.e. 110, 117, 125. Use the light bulb in series to learn which leads are which.

2) You cannot hook the 16 volt side to a 117 volt source safely. The trasformer will saturate and look like a short. That's what blew the circuit breaker/fuse. For an instant you will get a very high voltage on the 117 volt secondary which may breakdown,
arc and/or catch fire. Don't bother limiting the current. Too dangerous to play with.

3) Ultrasonic. This is possible but you must have a receiving transducer receiver and an ultrasonic source (no problem. just one 555 chip), an audio mixer circuit, and an simple audio preamp/amp and you're set to go.
Rick



Tim Hart wrote:

{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\11\10@181748 by llile

flavicon
face
>I have a transformer with 4 leads on the AC side and 6 on the output
side.  I'm a bit confused...I'm used to 2 on the input side and 3 on the
output.  Any idea how to even test the transformer?  I tried measuring the
ohms....they are all very close....

Usually this is done with a Variac, a variable AC transformer.  Connect to
a pair of leads and slooowly turtn it up from zero to mains voltage while
monitoring input current and output voltage.  Try connecting this to the
highest impedance leads first, most likely to be the high voltage input.
You simply have multiiple taps that produce several AC voltages.  Often
the input leads will be a different kind of wire.  Other than that you can
use the ol' circuit breaker method (ka POW!)

If you know the rated input wattage, you can also do a shorted test.  You
short the output leads, and turn up the input voltage until it draws rated
wattage, then measure the output current to get an estimate of the rated
output current.  This is, of course, a dangerous test if you don't know
the rated wattage......



>Another transformer I have is 110 to 16 volt...I hooked it up backward to
see if I could get a few hundred volts AC...nope...it popped my circuit
breaker....why did it not act as a step up?  Do I need to limit the
current I feed it?

Well, several things could have happened.  First, your low voltage winding
is liable to be low resistance resulting in large currents, blowing a
breaker.  Second, if that doesn't happen, you likely exceeded the voltage
rating of the windings on your high voltage windings, causing them to arc,
and short, once again blowing a breaker.  You really need to be using a
variac with this sort of thing.  You can fake it with a set of known low
voltage AC transformers - test at 6V then 12V then 48VAC then twice 48VAC
etc.  Or, <sarcasm = on> you can simply excercise your circuit breakers a
lot </sarcasm>


>And hearing Ultrasonic.  I want to audibly hear the output of a
ultrasonic transmitter....can I build an amp that shifts the frequence
down to a level I can hear via a speaker?  Any ideas?

A crude way might be to set up a comparator to convert the ultreasonics to
a square wave, then measure the pulse widths with a PIC, and
simultaneously output every third pulse with the PW multiplied by three
(or some number)    You could record the stuff directly into a memory
using A/D then play it back later at a lower baud rate...  You could
record it on magnetic tape and play it back a t a lower speed like us old
timers did (got any reel-to-reel tape players laying around?)  there might
be a way to hack one of those keen sound chips to record at a high data
rate and play back at a low data rate...

>Thanks for hearing me out...I know these are newbie questions....

Pun taken.

-- Lawrence Lile





Tim Hart <spam_OUTTim.HartTakeThisOuTspamHAWORTH.COM>
Sent by: pic microcontroller discussion list <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
11/10/2003 04:44 PM
Please respond to pic microcontroller discussion list


       To:     PICLISTspamKILLspamMITVMA.MIT.EDU
       cc:
       Subject:        [OT]: Simple questions...


HI all...I have a few quick simple questions for the group...

I have a transformer with 4 leads on the AC side and 6 on the output side.
I'm a bit confused...I'm used to 2 on the input side and 3 on the output.
Any idea how to even test the transformer?  I tried measuring the
ohms....they are all very close....

Another transformer I have is 110 to 16 volt...I hooked it up backward to
see if I could get a few hundred volts AC...nope...it popped my circuit
breaker....why did it not act as a step up?  Do I need to limit the
current I feed it?

And hearing Ultrasonic.  I want to audibly hear the output of a ultrasonic
transmitter....can I build an amp that shifts the frequence down to a
level I can hear via a speaker?  Any ideas?

Thanks for hearing me out...I know these are newbie questions....

Thanks,
Tim

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.



--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\11\11@131032 by Tim Hart

flavicon
face
The light bulb testing method is genus!  A short would just light the bulb brighter and I can test the output either way!  I like it!!!

The reason I was wanting to run the 110/16 backward was to build a flash capacitor charging transformer.  Maybe I need to get the 300 Volts DC a different way....?

The 555 transmitter and a normal amp as a receiver doesn't make much sense....I think I can build the transmitter once I figure out the HZ needed...maybe even use the PIC for that....but the receiver is confusing.  How do you stretch out the sound so it's in the human audible range??

And I can't really record it....it's a real (or very close) time event I'm trying to listen to...  I have Software on my PC I could shift the sound...but by the time it's on the PC the event is long gone!!

Thanks for the great info!!
Tim

>>> .....rixyKILLspamspam.....VVALLEY.COM 11/10/03 05:16PM >>>
I'll try to answer some of your questions.

1) Some transformers have two primaries. This allows hooking them up in series for 240 volt operation. You must have them wired "in phase" or it will overheat the transformer and damage it. Sometimes there is a color code, sometimes numbers. Sometimes you
can find a datasheet online or from the vendor. You can also test it "trial and error" with a 25 watt light bulb. **Be careful with dangerous voltages*** With an ohmeter, pair off the two primaries. Parallel the inputs and put the bulb in series as if it
were a fuse. If it lights bright, its hooked up wrong. Reverse one set of windings and the light should not light. Check for proper output voltage on the secondary. You now have it wired in phase. Depending on your current demand you may get away with
using just one primary, but the efficiency is somewhat reduced.
There is also the chance that there is only one primary with taps for different mains voltages. i.e. 110, 117, 125. Use the light bulb in series to learn which leads are which.

2) You cannot hook the 16 volt side to a 117 volt source safely. The trasformer will saturate and look like a short. That's what blew the circuit breaker/fuse. For an instant you will get a very high voltage on the 117 volt secondary which may breakdown,
arc and/or catch fire. Don't bother limiting the current. Too dangerous to play with.

3) Ultrasonic. This is possible but you must have a receiving transducer receiver and an ultrasonic source (no problem. just one 555 chip), an audio mixer circuit, and an simple audio preamp/amp and you're set to go.
Rick



Tim Hart wrote:

{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

2003\11\11@155635 by Rick C.
flavicon
face
The concept for the ultrasonic receiver is simple. Treat it just like an AM radio. The antenna is the receive transducer. The 555 is the local oscillator, a summing amp is the mixer. A low pass filter is the IF amp. A one chip speaker amp is all you need to hear it.

If you know about what frequency you want to hear, tune the 555 to oscillate a few kilohertz away from it. No more than 8 khz.

Forget the PIC. You will be knee deep with code you won't really need.
Rick

Tim Hart wrote:

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2003\11\11@161124 by Tim Hart

flavicon
face
I found some "Bat Detector" circuits that seem to be exactly what I'm wanting to do.  I'm still lost as to why a local signal mixed with an ultrahigh signal makes something you can hear?

They are used an LMC567 "Phase Locked Loop IC" to make the local oscillations.  Which is Greek to me...  I've used the LM386 before so I'm cool with that...but the rest still doesn't make much sense.

Maybe you can make sense of it...
http://www.njsas.org/projects/bat_detector/populel_sch.html
I appreciate the help!!!
Tim

>>> @spam@rixyKILLspamspamVVALLEY.COM 11/11/03 02:57PM >>>
The concept for the ultrasonic receiver is simple. Treat it just like an AM radio. The antenna is the receive transducer. The 555 is the local oscillator, a summing amp is the mixer. A low pass filter is the IF amp. A one chip speaker amp is all you need to hear it.

If you know about what frequency you want to hear, tune the 555 to oscillate a few kilohertz away from it. No more than 8 khz.

Forget the PIC. You will be knee deep with code you won't really need.
Rick

Tim Hart wrote:
email KILLspamlistservKILLspamspammitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email RemoveMElistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body

2003\11\11@163831 by Rick C.

flavicon
face
Like I said, it's just like an AM radio. Same principle. The same principle with receiving morse code in the amateur radio bands. A transmitter sending code on 7040 khz can be heard as a 1 khz on/off tone if your receiver is tuned to 7041 khz. The term is hetrodyne.
Rick

Tim Hart wrote:

> I found some "Bat Detector" circuits that seem to be exactly what I'm wanting to do.  I'm still lost as to why a local signal mixed with an ultrahigh signal makes something you can hear?
>
> They are used an LMC567 "Phase Locked Loop IC" to make the local oscillations.  Which is Greek to me...  I've used the LM386 before so I'm cool with that...but the rest still doesn't make much sense.
>
> Maybe you can make sense of it...
> http://www.njsas.org/projects/bat_detector/populel_sch.html
>
> I appreciate the help!!!
> Tim

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spamBeGonelistservspamBeGonespammitvma.mit.edu with SET PICList DIGEST in the body

2003\11\11@172234 by Rick C.

flavicon
face
Just looked at the bat detector schematic. It's just lie I explained. The LM567 is the oscillator. Q1 and Q2 make up a preamp and high pass filter. Both feed the fet mixer Q3 via R7/C2 and R11/C5. The resultat "tone" or ticking is amplified by U1. Simple.
Rick

Tim Hart wrote:

> I found some "Bat Detector" circuits that seem to be exactly what I'm wanting to do.  I'm still lost as to why a local signal mixed with an ultrahigh signal makes something you can hear?
>
> They are used an LMC567 "Phase Locked Loop IC" to make the local oscillations.  Which is Greek to me...  I've used the LM386 before so I'm cool with that...but the rest still doesn't make much sense.
>
> Maybe you can make sense of it...
> http://www.njsas.org/projects/bat_detector/populel_sch.html
>
> I appreciate the help!!!
> Tim

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email TakeThisOuTlistservEraseMEspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2003\11\12@042859 by Alan B. Pearce

face picon face
>The reason I was wanting to run the 110/16 backward was to
>build a flash capacitor charging transformer.  Maybe I
>need to get the 300 Volts DC a different way....?

Start with a transformer designed for a valve based power amplifier. That
will provide this sort of voltage real easy. You may even be able to salvage
something from an item bought at a hamfest or garage sale (yard sale in the
USA?).

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestspamTakeThisOuTmitvma.mit.edu

2003\11\12@111204 by Tim Hart

flavicon
face
Thanks for the help...I'll go google this "heterodyne" thing and see how it works...:)

>>> rixyEraseMEspam.....VVALLEY.COM 11/11/03 03:38PM >>>
Like I said, it's just like an AM radio. Same principle. The same principle with receiving morse code in the amateur radio bands. A transmitter sending code on 7040 khz can be heard as a 1 khz on/off tone if your receiver is tuned to 7041 khz. The term is hetrodyne.
Rick

Tim Hart wrote:

> I found some "Bat Detector" circuits that seem to be exactly what I'm wanting to do.  I'm still lost as to why a local signal mixed with an ultrahigh signal makes something you can hear?
>
> They are used an LMC567 "Phase Locked Loop IC" to make the local oscillations.  Which is Greek to me...  I've used the LM386 before so I'm cool with that...but the rest still doesn't make much sense.
>
> Maybe you can make sense of it...
> http://www.njsas.org/projects/bat_detector/populel_sch.html
>
> I appreciate the help!!!
> Tim

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspammitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestEraseMEspamEraseMEmitvma.mit.edu

2003\11\12@112245 by Tim Hart

flavicon
face
The heterodyne just sounds counterintuitive....
Ultra High + Local High = Low?

AM is a good example....I've not actually built an AM radio...but I guess it does the same thing.  Turns 600 AM into something I can hear.  One person out on the web converted an AM radio into a heterodyne....

I'll keep reading....it will "click" sooner or later....
Once again Thanks for the help!!!
Tim

>>> RemoveMErixyspam_OUTspamKILLspamVVALLEY.COM 11/11/03 04:22PM >>>
Just looked at the bat detector schematic. It's just lie I explained. The LM567 is the oscillator. Q1 and Q2 make up a preamp and high pass filter. Both feed the fet mixer Q3 via R7/C2 and R11/C5. The resultat "tone" or ticking is amplified by U1. Simple.
Rick

Tim Hart wrote:

> I found some "Bat Detector" circuits that seem to be exactly what I'm wanting to do.  I'm still lost as to why a local signal mixed with an ultrahigh signal makes something you can hear?
>
> They are used an LMC567 "Phase Locked Loop IC" to make the local oscillations.  Which is Greek to me...  I've used the LM386 before so I'm cool with that...but the rest still doesn't make much sense.
>
> Maybe you can make sense of it...
> http://www.njsas.org/projects/bat_detector/populel_sch.html
>
> I appreciate the help!!!
> Tim

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email RemoveMElistservTakeThisOuTspamspammitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com hint: To leave the PICList
EraseMEpiclist-unsubscribe-requestspamspamspamBeGonemitvma.mit.edu

2003\11\12@125243 by Denny Esterline

picon face
When you mix the freqs you get a very dirty signal that contains the
sum freq (extremely high) and the difference freq (low, usually audio)
Considering the enormous difference between these two components they
are very easy to separate with lowpass filters.

(do I here a "click" yet?) :-)

-Denny

{Original Message removed}

2003\11\12@143255 by Tim Hart

flavicon
face
That explains the "low pass filter" needed at the end...ditch the extremely high ones and keep the lower ones.  Odd behavior but I think I have it down now!!  Thanks!!!

>>> RemoveMEfirmwareKILLspamspamTDS.NET 11/12/03 11:51AM >>>
When you mix the freqs you get a very dirty signal that contains the
sum freq (extremely high) and the difference freq (low, usually audio)
Considering the enormous difference between these two components they
are very easy to separate with lowpass filters.

(do I here a "click" yet?) :-)

-Denny

{Original Message removed}

2003\11\12@143506 by Rick C.

flavicon
face
I don't know how dirty, it contains the fundamental (the receive carier),
the reference (local oscillator), the sum and product of the two mixed
signals. Once you grasp that concept, you understand how a radio receiver
works. Delving deeper off topic, since you want the modulated information
(in the case of an AM broadcast receiver), the reference oscillator (or
local oscillator) generates a frequency 455 khz above or below the desired
listening signal. The "intermediate frequency" amplifier passes only the
sum or product and attenuates the local oscillator and receive frequency.
This acts just like a hi/low pass filter more commonly known as a band
pass filter. It also increases your selectivity by the sharpness, or
stages of IF amplification. The signal is then demodulated by means of a
diode to remove the IF frequency and what is left behind is your AM audio
information that was broadcast....
There.. now you know how a superhetrodyne AM receiver works.
Rick C.
Chief Engineer - WTRM-FM


Denny Esterline wrote:

> When you mix the freqs you get a very dirty signal that contains the
> sum freq (extremely high) and the difference freq (low, usually audio)
> Considering the enormous difference between these two components they
> are very easy to separate with lowpass filters.
>
> (do I here a "click" yet?) :-)
>
> -Denny
>
> {Original Message removed}

2003\11\12@145335 by Denny Esterline

picon face
Clearly you're much more familiar with it than I, and I'll accept
your, thourough, description. My use of the term "dirty" was only ment
to imply "it contains many things, some you want, some you filter
out".

Either way, I think it "clicked" in the OP's mind, so it's all good.
:o)

-Denny


> I don't know how dirty, it contains the fundamental (the receive
carier),
> the reference (local oscillator), the sum and product of the two
mixed
> signals. Once you grasp that concept, you understand how a radio
receiver
> works. Delving deeper off topic, since you want the modulated
information
> (in the case of an AM broadcast receiver), the reference oscillator
(or
> local oscillator) generates a frequency 455 khz above or below the
desired
> listening signal. The "intermediate frequency" amplifier passes only
the
> sum or product and attenuates the local oscillator and receive
frequency.
> This acts just like a hi/low pass filter more commonly known as a
band
> pass filter. It also increases your selectivity by the sharpness, or
> stages of IF amplification. The signal is then demodulated by means
of a
> diode to remove the IF frequency and what is left behind is your AM
audio
> information that was broadcast....
> There.. now you know how a superhetrodyne AM receiver works.
> Rick C.
> Chief Engineer - WTRM-FM
>
>
> Denny Esterline wrote:
>
> > When you mix the freqs you get a very dirty signal that contains
the
> > sum freq (extremely high) and the difference freq (low, usually
audio)
> > Considering the enormous difference between these two components
they
> > are very easy to separate with lowpass filters.
> >
> > (do I here a "click" yet?) :-)
> >
> > -Denny
> >
> > {Original Message removed}

More... (looser matching)
- Last day of these posts
- In 2003 , 2004 only
- Today
- New search...