Put it together on your own, its called learning.
When I was experimenting with thousands of projects I had drawers and drawers of projects just sitting there after building and experimenting on each one.
I read the books, did it my self, and then did it mostly my way.
If some one suggested it couldn’t be done, I did it any way to learn if that was true, how, and why.
And If it burnt out a dime chip, six times in the finding, so what.
That’s what an educations is, removing the blinders and going for it.
When an optical transmitter experiment stated quite clearly “good for several feetâ€
6 Radios to One Speaker?
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positronicle
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- Contact:
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Chris Smith
- Posts: 4325
- Joined: Tue Dec 04, 2001 1:01 am
- Location: Bieber Ca.
Actually were are discussing your learning abilities and curve.
I have described the circuit but your having problems with the words.
A full bridge rectifier on a secondary can only go one way successfully.
AC in and DC out.
And its no where near the forth stage as the second stage first produces AC which is converted into DC pulsating and then its on into the tertiary transformer which then produces AC in the forth stage for the speaker.
Your simple Out put from the secondary is AC which goes into a Rectifier, there it is rectified into DC which feed the tertiary transformer that converts the signal back into AC for the speaker, it doesn’t get any simpler.
And no I dont post or print circuits.
I have described the circuit but your having problems with the words.
A full bridge rectifier on a secondary can only go one way successfully.
AC in and DC out.
And its no where near the forth stage as the second stage first produces AC which is converted into DC pulsating and then its on into the tertiary transformer which then produces AC in the forth stage for the speaker.
Your simple Out put from the secondary is AC which goes into a Rectifier, there it is rectified into DC which feed the tertiary transformer that converts the signal back into AC for the speaker, it doesn’t get any simpler.
And no I dont post or print circuits.
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positronicle
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- Contact:
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Chris Smith
- Posts: 4325
- Joined: Tue Dec 04, 2001 1:01 am
- Location: Bieber Ca.
Sounds like the Ouija board talking.
My cad programs and electronic drawing programs are needed by those who have trouble reading the B&W print.
I don’t cater in that direction no matter what their level of understanding is.
When it comes to soft ware, educating others on how to use it makes more sense, than holding hands with just a few starters into the trade.
I don’t work with the past any more, I leave that to the bright upstarts because its like digging a ditch, good for kids and those who never learn to do things different.
If I pick up a soldering iron its for R&D projects, not learning the basics.
Its way too old and nostalgic for me to return back to the 70s and 80s just because you don’t understand.
My cad programs and electronic drawing programs are needed by those who have trouble reading the B&W print.
I don’t cater in that direction no matter what their level of understanding is.
When it comes to soft ware, educating others on how to use it makes more sense, than holding hands with just a few starters into the trade.
I don’t work with the past any more, I leave that to the bright upstarts because its like digging a ditch, good for kids and those who never learn to do things different.
If I pick up a soldering iron its for R&D projects, not learning the basics.
Its way too old and nostalgic for me to return back to the 70s and 80s just because you don’t understand.
Chris Smith wrote:
A full bridge rectifier on a secondary can only go one way successfully.
AC in and DC out.
And its no where near the forth stage as the second stage first produces AC which is converted into DC pulsating and then its on into the tertiary transformer which then produces AC in the forth stage for the speaker.
Your simple Out put from the secondary is AC which goes into a Rectifier, there it is rectified into DC which feed the tertiary transformer that converts the signal back into AC for the speaker, it doesn’t get any simpler.
And no I dont post or print circuits.
Hi Chris,
What is hard to understand i think is how you expect to full wave
(or half wave) rectify sound into pulsating DC and then expect to
get a clear audio sound.
Once you full wave rectify an ac signal you immediately loose the
fundamental frequency...for example 60Hz input to a bridge
rectifier (four diodes) the output is completely void of 60Hz, with
the lowest frequency component being 120Hz (double the input).
This of course means mucho distortion.
Feed that into a transformer primary, and yes, the output is ac and
yes it's symetrical about zero too, but the distortion is going to be
so high no one is going to want to listen to it.
Feed that into a speaker and it's basically the same thing.
Feed the rectifier output to the speaker directly and it's still the same.
Maybe the distortion is high but it still works to some degree?
Is this what you are saying?
LEDs vs Bulbs, LEDs are winning.
I'm looking at eBay to purchase the resistors I'll use for this project, but I'm a little confused. I see many different types, such as Carbon, Wire Wound, Metal Film, Ceramic, Carbon Film, Thick Film... Is there a specific type I should use for this application?Stevereno wrote:I'm going to try setting it up as per the schematic above. Sure looks easy enough. Thanks Miguel!Externet wrote:Until a better schematic shows up ;
R1+------10K---------S-------->AMP SPK
R2+------10K---------S
R3+------10K---------S
.
.
R6+------10K---------S
R1+ means radio 1 speaker + terminal. etc
S is the sum node, all S tied together fed to the amplified speaker input.
Miguel
Hi again,
Hee hee...
I decided to do a quick simulation. I used a 4v peak ac 5000Hz
signal as the signal source, but i had a 1v, 25kHz ac riding on that.
The reason for the second frequency is to simulate an audio signal,
which is made up of several frequencies not just one.
The transformer was made up of two coupled inductors and
the core material was something like Magnetics Inc. J type material.
This material isnt made for audio frequencies, so i had to keep
the signal generator frequencies a bit higher than most audio, but
the general principles will still apply with lower frequency type core
materials and real audio.
The transformer, with pure ac (4v peak 5kHz ac plus 1v peak 25kHz ac)
fed to the input works as expected. Since i used a 1 to 1 ratio the
output was pretty much the same as the input, with a tiny amount
of distortion which is expected, but the output looked very much like
a sine wave. The load was maintained at 10 ohms to simulate a
speaker (with 10 ohms instead of 8 ohms its easier to calculate
current from voltage or vice versa).
Inserting a high speed diode between signal source (same two freqs)
and transformer primary, the output looked like a half wave rectified
sine wave for the lower frequency, and for the parts that were not
flat the higher frequency (25kHz showed up riding on the wave just
as if you simple cut half of the whole wave off. The only difference is
that the wave, although the flat parts start out close to zero volts,
they work up to some level so that the zero of the output now becomes
part way down the half sine wave. In other words, the wave centers
itself about zero even though it looks like a half wave sine wave.
The distortion for the lower frequency is absolutely terrible, and
since the wave is flat for 1/2 of the lower frequency cycle, this means
half of all the upper frequency (25kHz) cycles are simply missing
altogether. For the 25kHz cycles that do make it to the output, they
seem approximately like the input so there is less distortion during
these half cycles. To hear this output in an actual speaker would be
interesting.
Next, a bridge rectifier made from high speed diodes was used
inbetween the signal generator and the transformer primary.
What happened here is that the low frequency (5kHz) rectified
to 10kHz and looked pretty much like what a power supply full
wave rectified sine wave looks like, while the high frequency
passed again with less distortion.
What this seems to indicate is that the lowest frequency gets
rectifed while the higher frequencies can pass without as much
problem. This would cause high distortion in the lowest frequency
component and less in the higher frequency components of an
actual audio signal. Because an audio signal can have its lowest
frequency vary depending on the content, i would expect some
very strange results although there is the possibility that one could
understand spoken language even so. In other words, it would
have to be tried and listened to in order to get an idea just how
feasible this would be in real life, and the volume could be varied
to get a high signal to noise ratio because at low volume settings
there is bound to be way too much distortion.
There is one other aspect however, that was not mentioned yet.
That is, when the primary of a transformer is run with either half
or full wave rectified sine wave, a primary dc current develops
because the wave is always on one side of zero and never crosses.
This develops what is referred to in the power supply industry
as "net dc in the primary", and is for the most part taboo because
it causes unnecessary power heating in the primary winding.
If, as the volume is cranked up to reduce overall distortion,
the primary current becomes great enough it may overheat the
transformer, but that's only one of the problems. Because the
current wave is peaked (sine peaks) and these peaks ride on
that average dc level, the current draw from the amplifier will
be much greater at the peaks than it normally would be, which
can cause clipping (even more distortion) and possibly even draw
too much current from the amplifier.
From the above it seems that there are a host of problems that
could arise. Getting the right combination might be difficult.
Even so, it would be interesting to hook up and try, just to see
what the audio would sound like from various sources like
music and spoken text.
Hee hee...
I decided to do a quick simulation. I used a 4v peak ac 5000Hz
signal as the signal source, but i had a 1v, 25kHz ac riding on that.
The reason for the second frequency is to simulate an audio signal,
which is made up of several frequencies not just one.
The transformer was made up of two coupled inductors and
the core material was something like Magnetics Inc. J type material.
This material isnt made for audio frequencies, so i had to keep
the signal generator frequencies a bit higher than most audio, but
the general principles will still apply with lower frequency type core
materials and real audio.
The transformer, with pure ac (4v peak 5kHz ac plus 1v peak 25kHz ac)
fed to the input works as expected. Since i used a 1 to 1 ratio the
output was pretty much the same as the input, with a tiny amount
of distortion which is expected, but the output looked very much like
a sine wave. The load was maintained at 10 ohms to simulate a
speaker (with 10 ohms instead of 8 ohms its easier to calculate
current from voltage or vice versa).
Inserting a high speed diode between signal source (same two freqs)
and transformer primary, the output looked like a half wave rectified
sine wave for the lower frequency, and for the parts that were not
flat the higher frequency (25kHz showed up riding on the wave just
as if you simple cut half of the whole wave off. The only difference is
that the wave, although the flat parts start out close to zero volts,
they work up to some level so that the zero of the output now becomes
part way down the half sine wave. In other words, the wave centers
itself about zero even though it looks like a half wave sine wave.
The distortion for the lower frequency is absolutely terrible, and
since the wave is flat for 1/2 of the lower frequency cycle, this means
half of all the upper frequency (25kHz) cycles are simply missing
altogether. For the 25kHz cycles that do make it to the output, they
seem approximately like the input so there is less distortion during
these half cycles. To hear this output in an actual speaker would be
interesting.
Next, a bridge rectifier made from high speed diodes was used
inbetween the signal generator and the transformer primary.
What happened here is that the low frequency (5kHz) rectified
to 10kHz and looked pretty much like what a power supply full
wave rectified sine wave looks like, while the high frequency
passed again with less distortion.
What this seems to indicate is that the lowest frequency gets
rectifed while the higher frequencies can pass without as much
problem. This would cause high distortion in the lowest frequency
component and less in the higher frequency components of an
actual audio signal. Because an audio signal can have its lowest
frequency vary depending on the content, i would expect some
very strange results although there is the possibility that one could
understand spoken language even so. In other words, it would
have to be tried and listened to in order to get an idea just how
feasible this would be in real life, and the volume could be varied
to get a high signal to noise ratio because at low volume settings
there is bound to be way too much distortion.
There is one other aspect however, that was not mentioned yet.
That is, when the primary of a transformer is run with either half
or full wave rectified sine wave, a primary dc current develops
because the wave is always on one side of zero and never crosses.
This develops what is referred to in the power supply industry
as "net dc in the primary", and is for the most part taboo because
it causes unnecessary power heating in the primary winding.
If, as the volume is cranked up to reduce overall distortion,
the primary current becomes great enough it may overheat the
transformer, but that's only one of the problems. Because the
current wave is peaked (sine peaks) and these peaks ride on
that average dc level, the current draw from the amplifier will
be much greater at the peaks than it normally would be, which
can cause clipping (even more distortion) and possibly even draw
too much current from the amplifier.
From the above it seems that there are a host of problems that
could arise. Getting the right combination might be difficult.
Even so, it would be interesting to hook up and try, just to see
what the audio would sound like from various sources like
music and spoken text.
LEDs vs Bulbs, LEDs are winning.
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Robert Reed
- Posts: 2277
- Joined: Wed Nov 24, 2004 1:01 am
- Location: ASHTABULA,OHIO
- Contact:
Years ago I had a bunch of radios and scanners connected to a diode mixer that was fed into an to a amplifier.
several channels were too loud so I tried to attenuate them.
The speaker cabinet for voice had a midtone 8 inch speaker that sounded much better than the audio from the radios.
The antenna system made significant improvement in the readability of faint signals but the headphones were always the best so AGC to limit the headphone volume.
I should have had AGC and squelch on every channel along with voice filter and an indicator light for each channel. It was that one CB channel that I needed to at times manually switch on the attenuater made of three resistors.
several channels were too loud so I tried to attenuate them.
The speaker cabinet for voice had a midtone 8 inch speaker that sounded much better than the audio from the radios.
The antenna system made significant improvement in the readability of faint signals but the headphones were always the best so AGC to limit the headphone volume.
I should have had AGC and squelch on every channel along with voice filter and an indicator light for each channel. It was that one CB channel that I needed to at times manually switch on the attenuater made of three resistors.
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Chris Smith
- Posts: 4325
- Joined: Tue Dec 04, 2001 1:01 am
- Location: Bieber Ca.
The reason you waste your time is mentioned above, some amps do work especially voice communication amps such as the 75 volt intercom.
Having done this [similar] in the 90s with two amps, I found one quite satisfactory while the other did not come through for the most part.
That is why I say try it, it MAY work.
Most intercoms “screechâ€
Having done this [similar] in the 90s with two amps, I found one quite satisfactory while the other did not come through for the most part.
That is why I say try it, it MAY work.
Most intercoms “screechâ€
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dyarker
- Posts: 1924
- Joined: Fri Aug 22, 2003 1:01 am
- Location: Izmir, Turkiye; from Rochester, NY
- Contact:
The transformers are 100 Ohm to 100 Ohm Center Tap (the primary side may be CT, but that doesn't matter). The voltage at the scanner speaker output is much larger than needed to drive an amplified speaker, so this circuit lowers signal voltage in three places. Using the secondary CT causes a 0.7 step down. The 4.7K feedback with 10K input resistors, lowers the signal again by a little more than half. Then the 2K output pot.
The scanners should have no problem driving a higher impedance without distortion. If there is a problem, then use the resistors shown in gray. Something between 16 and 50 Ohms should be enough loading. If no problem, then leave them out.
It may also be possible to leave out the 1K resistors. Their purpose is to lower the impedance enough so the circuit is not such a good antenna for noise pick-up.
For the op amp I suggest a TLC081. It is a single supply amp with 16V max supply. This will let you use the same 12V that supplies the Motorola Amp/Speaker.The two vertical 10K resistors bias the output to half the supply voltage. The 10uF is supply filter. The 1uF blocks DC from the output.
Dale Y
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Chris Smith
- Posts: 4325
- Joined: Tue Dec 04, 2001 1:01 am
- Location: Bieber Ca.
The only problem here that I see is,.... where does the out put get its gain or Watt/ Amperage? [over all volume]
The op amp is a set of diodes and other circuits which will give you the separation from feed back and integrity, but with several 10 k resistors in line at the feed positive, and a op amp that can signal but cant carry the power, where does the finals get their real power? [Wattage?]
Im sure in low power situations it will talk to you just fine, but with the 75 volt system it will scream at you?
Unfortunately I cant speak for his scanner outputs as my situation was two 75 volt PA systems on the out put.
The op amp is a set of diodes and other circuits which will give you the separation from feed back and integrity, but with several 10 k resistors in line at the feed positive, and a op amp that can signal but cant carry the power, where does the finals get their real power? [Wattage?]
Im sure in low power situations it will talk to you just fine, but with the 75 volt system it will scream at you?
Unfortunately I cant speak for his scanner outputs as my situation was two 75 volt PA systems on the out put.
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