Using Ohm's law for creating a multiplying mixer?

N

Nils Beyer

Guest
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|>
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider


Cheers,
Nils
 
On Mon, 24 May 2004 01:36:51 +0200, "Nils Beyer" <NilsBeyer@web.de> posted this:

I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?
Click to expand...
Yes, you are mistaken. Frequencies have very little in common with Ohms
law.

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider


Cheers,
Nils
Click to expand...
If the circuit above is operating in a linear fashion, there will be no
multiplication of frequencies. There will be only addition so that FO=F1+F2 and
not F1*F2.

Multiplication will happen if F1 and F2 are passed simultaneously
through a non-linear element.

+5V
O
|
| The voltages of F1 and F2
.-. need to be high enough
| | R3 to cause currents to flow
'-' only during part of their
|----- FO 360 degree cycles.
R1 |
___ |/ The transistor is then
F1 --|___|---| T1 operating in a non-linear
___ | |> fashion and multiplication
F2 --|___|- | will happen.
|
R2 |
---
-

Jim
 
On Mon, 24 May 2004 02:44:45 GMT, James Meyer wrote:

On Mon, 24 May 2004 01:36:51 +0200, "Nils Beyer" <NilsBeyer@web.de> posted this:

I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Yes, you are mistaken. Frequencies have very little in common with Ohms
law.


Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider


Cheers,
Nils


If the circuit above is operating in a linear fashion, there will be no
multiplication of frequencies. There will be only addition so that FO=F1+F2 and
not F1*F2.

Multiplication will happen if F1 and F2 are passed simultaneously
through a non-linear element.

+5V
O
|
| The voltages of F1 and F2
.-. need to be high enough
| | R3 to cause currents to flow
'-' only during part of their
|----- FO 360 degree cycles.
R1 |
___ |/ The transistor is then
F1 --|___|---| T1 operating in a non-linear
___ | |> fashion and multiplication
F2 --|___|- | will happen.
|
R2 |
---
-

Jim
Click to expand...
'cept for this simple mixer, one signal is often fed into the
emitter.

And the op's further confused, possibly, on what really goes on in
der mixer, i.e., the multiplication of the two signals ( if it were
a true multiplier ) results in a number of components which include
F1 + F2 *and* F1 - F2, not F1 * F2 ... it's x(t) * y(t)

Actually, the multiplication in this case is a result of the
addition of the two voltage signals. Taking advantage of the b-e
diode's square law simplification, I = a[Vdc + x(t) + y(t)]^2, you
end up with among other things two sine waves being multiplied which
yields two sines of the sum and difference.

A
--
Best Regards,
Mike
 
"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider
Click to expand...
It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.


--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
On Mon, 24 May 2004 09:33:41 +0200, Frank Bemelman wrote:

"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider

It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.
Click to expand...
The F U theory, right?
--
Best Regards,
Mike
 
James Meyer <jmeyer@nowhere.com> wrote in message news:<k8n2b0lutngh2ngoq3vmqcpn84tu9bo7c0@4ax.com>...
On Mon, 24 May 2004 01:36:51 +0200, "Nils Beyer" <NilsBeyer@web.de> posted this:

snip

Yes, you are mistaken. Frequencies have very little in common with Ohms
law.
Click to expand...
<snip>

It would be better to insist on the realistic

V/Z = I

At the least qualitatively, right from the start, rather than the "unachievable"

V/R = I



Cheers
Robin
 
"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:9ld9tdfvvur2.dlg@news.individual.net...
On Mon, 24 May 2004 09:33:41 +0200, Frank Bemelman wrote:

"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's
nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider

It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.

The F U theory, right?
Click to expand...
There is nothing wrong with the principle of the idea. Convert
one frequency to a resistance, another to a current, let those
work on each other, enjoy Ohms Law at work, and convert the resulting
voltage to a frequency again.

If it is practical, is another issue.

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
First, thanks to you all James, Mike, Frank and Robin for your replies.

I would really like to know how such a (F1->R)*(F2->I)-circuit would look
like.

You're right, Frank, if it would be practical, that's another question
but I would understand it then. I can't understand why a diode-ring-
mixer works:

1)


. |
.--------o--|>|--o-------.
!!( | ' | | )!!
-----. !!( --- .-. )!! .-----
)!!( A V )!!(
F1 )!! --. '-' --- .-- !!( F2
)!!( | | | . | | )!!(
-----' !!( | o--|<|--o | )!! '-----
!!( | | | ' | | )!!
'-|------|-------' .-|-'
| '-----------' |
| |
--- O
FO

This circuit works. I've tried it in LTSpice. But the input amplitudes
must not be larger than around 700mV.

I don't understand what the inductors are good for. I understand the
purpose of the diodes like that:

2)
___
F1 ----|___|----. . |
___ o----|>|----o----O FO
F2 ----|___|----' ' | |
.-.
| |
'-'
|
---

For what are in circuit 1) the inductors good for?

Or what's about that circuit:
http://www.b-kainka.de/bastel96.htm

It's said there, that the frequency of the xtal is mixed with the radio
signal. Where's the mixer there? And why does it work?

I've also tried to simulate a Gilbert-Cell-Mixer but it doesn't work.
Neither the basic circuit nor the inner-circuit of the MC1496. I've
attached the whole LTSpice-.asc-file if you want to simulate it, too.


My three problems are:

a) I don't like ICs. Of course they work well but I can't learn anything.
And fun is less as these ICs are _not_ _my_ _creations_.

b) I don't like inductors as it's difficult for me to get the right henry-
value. Don't to say anything about making transformers on my own.

c) I don't have any variable capacitors.

So the best thing for me would be using only resistors, capacitors, bjts,
fets, diodes.


My primary goal is to build a nice FM-Radio using the range 80-110 MHz.
And using a circuit that I _understand_. Not something like this:
http://www.somerset.net/arm/fm_only_one_transistor_radio.html


In that circuit I understand nothing. First the understanding then the
tricks. ;-)

For my FM-Radio-experiment, I'd like to use the quadrator-demodulation
principle. And a modular built.


M1) RF Amp:
+5V
O
.-------o
| .-.
.-. | |
| | '-'
'-' o-----O ARF
|| | | /
RF ----||----o----|<
|| | >
o---.
.-. |
| | ===
'-' |
o---'
---

M2) Phase Shifter:

ARF ----o------------.
| |
.-. |
| | R1 === C1
'-' |
|---O -45° o---O +45°
| .-.
=== C2 | | R2
| '-'
| |
--- ---

R=R1=R2
C=C1=C2

1
R = -------------- with F=99.2 MHz [WDR2 ;-)]
2 x PI x F x C


M3) Mixer:

.---.
+45° ------| X |------O NF
'---'
-45° --. |
| |
--- |
ARF

M4) NF Amp:
_ _
.---. | \ .---. | \
NF ------|LPF|------| >------|LPF|------| >------O TRALALALALA
'---' |_/ '---' |_/



Automatic gain control would be cool and nice, but I don't know how
to do that. Does anyone of you know whre to get information and example
circuits for AGC?

Tuning (selecting radio frequencies and stations) would be changing the
phase-shifting circuit using a potentiometer as R for example, or?

So, my main problem is the X-mixing-circuit...


Cheers,
Nils




<- snip: Mixer_Tests.asc ->
Version 4
SHEET 1 2324 1188
WIRE 576 144 544 144
WIRE 576 224 544 224
WIRE 704 176 768 176
WIRE 768 176 768 288
WIRE 1184 144 1216 144
WIRE 1184 224 1216 224
WIRE 1056 176 992 176
WIRE 992 176 992 304
WIRE 816 192 816 208
WIRE 816 208 832 208
WIRE 816 128 816 112
WIRE 816 112 832 112
WIRE 896 112 912 112
WIRE 912 112 912 128
WIRE 912 192 912 208
WIRE 912 208 896 208
WIRE 816 112 816 96
WIRE 816 96 704 96
WIRE 704 256 912 256
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WIRE 1680 192 1744 192
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WIRE 2192 240 2192 192
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WIRE 1680 96 1680 48
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WIRE 1824 64 2016 64
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WIRE 1616 80 2320 80
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WIRE 1680 -96 1680 -112
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WIRE 2256 -112 2256 -96
WIRE 2256 -16 2256 64
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WIRE 2192 592 2192 560
WIRE 1744 464 1744 416
WIRE 2192 464 2192 416
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WIRE 1616 704 1616 672
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FLAG 144 208 0
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FLAG -16 128 MOD
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FLAG 544 224 0
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FLAG 1216 144 CAR
FLAG 1216 224 0
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FLAG -144 128 +5V
FLAG 1680 -112 +5V
FLAG 2256 -112 +5V
FLAG 1888 -16 GC1
FLAG 2016 -16 GC2
FLAG 1504 512 0
FLAG -256 128 0
FLAG -256 208 -5V
FLAG 1568 704 -5V
SYMBOL voltage -16 112 R0
WINDOW 3 -46 141 VLeft 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName MOD
SYMATTR Value SINE(0 1V 1kHz)
SYMBOL voltage 144 112 R0
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SYMATTR Value SINE(0 1V 100kHz)
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SYMATTR InstName AM
SYMATTR Value V=V(MOD)*V(CAR)
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SYMATTR InstName L1
SYMATTR Value {hen}
SYMATTR Type ind
SYMATTR SpiceLine Rser={rser}
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SYMATTR Value {hen}
SYMATTR Type ind
SYMATTR SpiceLine Rser={rser}
SYMBOL ind2 1040 192 M180
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SYMATTR Value {hen*4}
SYMATTR Type ind
SYMATTR SpiceLine Rser={rser}
SYMBOL ind2 1040 272 M180
WINDOW 0 36 80 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName L6
SYMATTR Value {hen*4}
SYMATTR Type ind
SYMATTR SpiceLine Rser={rser}
SYMBOL res 976 288 R0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL diode 832 96 M90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 896 128 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 896 224 M270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
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SYMATTR Value 1N4148
SYMBOL diode 832 192 R180
WINDOW 0 24 72 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName D4
SYMATTR Value 1N4148
SYMBOL npn 1616 96 R0
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SYMATTR Value 2N3904
SYMBOL npn 1888 96 M0
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SYMATTR Value 2N3904
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SYMATTR Value 2N3904
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SYMATTR Value 2N3904
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SYMATTR Value 2N3904
SYMBOL npn 1680 240 R0
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SYMATTR Value 2N3904
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SYMATTR InstName B1
SYMATTR Value V=V(GC1,GC2)
SYMBOL voltage -144 112 R0
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL res 2240 -112 R0
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SYMATTR Value 2N3904
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SYMATTR Value 500
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SYMATTR Value 500
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SYMBOL res 1600 576 R0
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SYMATTR Value 500
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SYMATTR Value 1k
SYMBOL res 1600 496 R90
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SYMATTR Value 6.8k
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TEXT -70 34 Left 0 !.tran 1ms startup
TEXT 560 64 Left 0 !K1 L1 L2 L3 1
TEXT 1200 64 Right 0 !K2 L4 L5 L6 1
TEXT 800 24 Left 0 !.param rser 25
TEXT 800 48 Left 0 !.param hen 1mH
<- snip: Mixer_Tests.asc ->
 
If you want any selectivity, in you FM radio, you will HAVE to use
a tuned circuit.
Even if you mix down from say 100MHz with a 90MHz osc. to a 10MHz IF, you
still have to get rid of the 80MHz input, it will also give 10MHz IF.
The lower the IF (as seen today), the more difficult this becomes.
One could perhaps use a very sensitive PLL at 100 MHz and use its error
voltage for the audio...
JP
 
"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2heja9Fc7h37U1@uni-berlin.de...
First, thanks to you all James, Mike, Frank and Robin for your replies.

I would really like to know how such a (F1->R)*(F2->I)-circuit would look
like.

You're right, Frank, if it would be practical, that's another question
but I would understand it then. I can't understand why a diode-ring-
mixer works:
Click to expand...
Neither can I ;) I know how an AM detector works, and that's about
it. Are you skipping chapters in your book ? ;-)

[snip]

It's said there, that the frequency of the xtal is mixed with the radio
signal. Where's the mixer there? And why does it work?
Click to expand...
Try this mixer in LT-spice, just for fun:

5V 10000Hz sine -----1K------.
|
5V 9990Hz sine -----1K------.-----|>|---.---------.--- OUT
| |
=== 22uF 1K
| |
GND ____________________________________|_________|____


a) I don't like ICs. Of course they work well but I can't learn anything.
And fun is less as these ICs are _not_ _my_ _creations_.

b) I don't like inductors as it's difficult for me to get the right henry-
value. Don't to say anything about making transformers on my own.

c) I don't have any variable capacitors.
Click to expand...
Yes, I sometimes try to boil potatoes without water too. It doesn't
always go very well ;)

[snip]

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
On Mon, 24 May 2004 13:15:03 +0200, Frank Bemelman wrote:

"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:9ld9tdfvvur2.dlg@news.individual.net...
On Mon, 24 May 2004 09:33:41 +0200, Frank Bemelman wrote:

"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a resistor,
and convert F1 to a resistance, perhaps using a transistor (what's
nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider

It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.

The F U theory, right?

There is nothing wrong with the principle of the idea. Convert
one frequency to a resistance, another to a current, let those
work on each other, enjoy Ohms Law at work, and convert the resulting
voltage to a frequency again.

If it is practical, is another issue.
Click to expand...
Let me try that again. That's the F [yo]U theory, right ? :)
--
Best Regards,
Mike
 
"Frank Bemelman" <f.bemelmanx@planet.invalid.nl> wrote:
Try this mixer in LT-spice, just for fun:

5V 10000Hz sine -----1K------.
|
5V 9990Hz sine -----1K------.-----|>|---.---------.--- OUT
| |
=== 22uF 1K
| |
GND ____________________________________|_________|____
Click to expand...

Mmm, 10Hz at output.

There's something you want to say, right? ;-)
But I can't see it now.


a) I don't like ICs. Of course they work well but I can't learn anything.
And fun is less as these ICs are _not_ _my_ _creations_.

b) I don't like inductors as it's difficult for me to get the right henry-
value. Don't to say anything about making transformers on my own.

c) I don't have any variable capacitors.

Yes, I sometimes try to boil potatoes without water too. It doesn't
always go very well ;)
Click to expand...
Yep, I think I'll have to fiddle around with that components even if I
don't like them. But are they so really neccessary like potatoe water?

No way to build a FM-radio without varicaps, inductors and ICs?


Heel veel dank, en meer suggesties zijn zeer welkom...


Cheers,
Uri
 
"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2heqtsFc6eeqU1@uni-berlin.de...
"Frank Bemelman" <f.bemelmanx@planet.invalid.nl> wrote:
Try this mixer in LT-spice, just for fun:

5V 10000Hz sine -----1K------.
|
5V 9990Hz sine -----1K------.-----|>|---.---------.--- OUT
| |
=== 22uF 1K
| |
GND ____________________________________|_________|____


Mmm, 10Hz at output.

There's something you want to say, right? ;-)
But I can't see it now.
Click to expand...
Well, it was not much different from your circuit you used as
an example to show your understanding of diodes. There are
many ways to build a mixer, and there are good reasons for
inductors and variable caps in radios, whether you like them
or not. I have no desire to build a radio myself, but if I
did, I would do some reading about such circuits, and try to
understand it. And probably quit after the 3rd chapter and
go out to buy a radio ;) But don't let that keep you from
trying...

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:1og6fp4rfo0mw.dlg@news.individual.net...
On Mon, 24 May 2004 13:15:03 +0200, Frank Bemelman wrote:

"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:9ld9tdfvvur2.dlg@news.individual.net...
On Mon, 24 May 2004 09:33:41 +0200, Frank Bemelman wrote:

"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a
resistor,
and convert F1 to a resistance, perhaps using a transistor (what's
nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider

It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.

The F U theory, right?

There is nothing wrong with the principle of the idea. Convert
one frequency to a resistance, another to a current, let those
work on each other, enjoy Ohms Law at work, and convert the resulting
voltage to a frequency again.

If it is practical, is another issue.

Let me try that again. That's the F [yo]U theory, right ? :)
Click to expand...
Yes, I understood the F*** Y*U but I don't see the joke here.
I was about as serious as I get ;)

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
"Nils Beyer" <NilsBeyer@web.de> wrote in message news:2heja9Fc7h37U1@uni-
You're right, Frank, if it would be practical, that's another question
but I would understand it then. I can't understand why a diode-ring-
mixer works:
SNIP CIRCUIT
This circuit works. I've tried it in LTSpice. But the input amplitudes
must not be larger than around 700mV.
^^^^^

I don't understand what the inductors are good for. I understand the
purpose of the diodes like that:

2)
___
F1 ----|___|----. . |
___ o----|>|----o----O FO
F2 ----|___|----' ' | |
.-.
| |
'-'
|
---
Click to expand...
I think there's more to it than that - if you look at the V spec,
that's right about where a diode is turning on - i.e. its
nonlinear range. This nonlinearity is what mixes the signals,
AIUI.

For what are in circuit 1) the inductors good for?
Click to expand...
Coupling, and making it balanced, I think.
 
"Nils Beyer" <NilsBeyer@web.de> wrote in message news:2heqtsFc6eeqU1@uni-berlin.de...
No way to build a FM-radio without varicaps, inductors and ICs?
Click to expand...
Even with the simplest designs you need at least one coil and variable cap or a varactor diode.
But the results are total crap (regenerative receiver).

I suggest using real coils-caps in a superhet. The intermediate frequency transformers are standard
and relatively easy
to get. You can take them out of an old receiver. The rest of the coils are just 4-5 turns of 1mm
Cu wire so are very easy to construct.

Disasemble an old transistor radio to get the variable caps. Or use varactor diodes, relatively easy
to get.

I strongly suggest starting with AM first.

SioL
 
On Mon, 24 May 2004 21:19:09 +0200, Frank Bemelman wrote:

"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:1og6fp4rfo0mw.dlg@news.individual.net...
On Mon, 24 May 2004 13:15:03 +0200, Frank Bemelman wrote:

"Activ8" <reply2group@ndbbm.net> schreef in bericht
news:9ld9tdfvvur2.dlg@news.individual.net...
On Mon, 24 May 2004 09:33:41 +0200, Frank Bemelman wrote:

"Nils Beyer" <NilsBeyer@web.de> schreef in bericht
news:2hcr0eFbf080U1@uni-berlin.de...
I'm a hobby electronic technican. So, don't expect anything based on
facts. ;-))



U = R * I
| | |
FO = F1 * F2


If it's possible to convert F2 to a current, perhaps using a
resistor,
and convert F1 to a resistance, perhaps using a transistor (what's
nothing
else but a current controlled resistor), then it must be possible to
multiply these two frequencies using Ohm's law, or am I wrong?

Sth. like that:
---------------

+5V
O
|
R1 |
___ |/
F1 --|___|--| T1
|
| R2
| ___
?? FO --o--|___|-- F2
|
.-.
| | R3
'-'
|
---
-

R1: converting V(F1) to I for controlling T1's resistance
R2: converting V(F2) to I
R3: build a voltage divider

It won't work. T1's resistance follows the F1 signal, changes
at the same speed of F1. Not a constant resistance that has
a relation with the frequency. The same applies to F2, it
is not converteted into a current.

If your F1 and F2 converters did work this way, you would have
gotten a signal U, not an FO yet, so you would still have to add
a voltage to frequency converter.

But your idea is okay, if you convert F1 and F2 properly, you
can use ohms law to get that 'U' which you can convert to F0.

The F U theory, right?

There is nothing wrong with the principle of the idea. Convert
one frequency to a resistance, another to a current, let those
work on each other, enjoy Ohms Law at work, and convert the resulting
voltage to a frequency again.

If it is practical, is another issue.

Let me try that again. That's the F [yo]U theory, right ? :)

Yes, I understood the F*** Y*U but I don't see the joke here.
I was about as serious as I get ;)
Click to expand...
And I'm Ted Nugent. Joke? More like word play.

But it really *is* an F U theory with the U being anyone who gets
suckered in to trying this out or rather using the above circuit to
demonstrate the concept, cause it will mix (no, multiply), but the
explaination won't fly.

--
Best Regards,
Mike
 
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