2 Transistor AM Radio

D

Dave.H

Guest
Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.


http://www.techlib.com/electronics/crystal.html#Simple2transistor
 
On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:
Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit.  I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor
Click to expand...
Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris
 
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:
On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris
Click to expand...
I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.
 
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:



On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.
Click to expand...
The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?
 
"Dave.H" (the1930s@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:



On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?
Click to expand...
Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael
 
On Feb 6, 12:47 am, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:



On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?
Click to expand...
Sorry for all the questions, but would a couple of BC547 transistors
work instead of the 2N2222 one shown in the picture? I can get
2N2222A but I'm not sure if they're compatible with 2N2222, due to the
similar names I'm guessing they are.
 
On Feb 6, 2:35 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:
"Dave.H" (the19...@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?

Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael
Click to expand...
Sorry, you've lost me here. The rod does have a single large winding.
 
On Feb 6, 2:35 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:
"Dave.H" (the19...@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?

Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael
Click to expand...
Sorry, you've lost me here. The rod does have a single large winding.
 
On Feb 6, 2:35 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:
"Dave.H" (the19...@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?

Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael
Click to expand...
Sorry, you've lost me here. The rod does have a single large winding.
 
On Feb 6, 2:35 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:
"Dave.H" (the19...@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?

Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael
Click to expand...
Sorry, you've lost me here. The rod does have a single large winding.
 
On 2/5/08 7:43 AM, in article
3a429b38-63e5-429e-8ad2-569cfa64ae97@q39g2000hsf.googlegroups.com, "Dave.H"
<the1930s@googlemail.com> wrote:

On Feb 6, 2:35 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:
"Dave.H" (the19...@googlemail.com) writes:
On Feb 5, 10:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:

On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit. I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave. If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick. As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap. Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question. The radio shown is fairly
simple, and shouldn't be too difficult to build. If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder). If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it. The transformer has three wires on one side, and
two on the other from what I can see in the picture.

The ferrite rod antenna I'm planning to use has four wires, how would
I hook this up the the tuning cap?

Chances are pretty good it alreayd has the needed pickup loop.

Likely one winding is quite large, and will resonate with the variable
capacitor. And then a small winding of a small number of turns to couple
the signal out of that resonant circuit.

Michael

Sorry, you've lost me here. The rod does have a single large winding.
Click to expand...
As you previously said, it has four wires coming from it. In this case it
means it has two windings. The winding you need to use, is the one with the
most wire. It is used to resonate with a (maximum) 365 pF variable
capacitor. The capacitor you have and want to use will not properly cover
the broadcast band (it won't tune into the lower end of the band). The
other two wires should be ignored, except do not connect them together.
 
Dave.H wrote:

<snip>

Sorry for all the questions, but would a couple of BC547 transistors
work instead of the 2N2222 one shown in the picture? I can get
2N2222A but I'm not sure if they're compatible with 2N2222, due to the
similar names I'm guessing they are.
Click to expand...
This looks like a fun project for you. Enjoy experimenting with it
and feel free about asking questions.

Yes, you can use the BC547 or the 2N2222A or most any small
NPN transistor. Be sure to get the leads right when you
connect them to the circuit. In the schematic, the transistor
is drawn with an arrow in the emitter lead pointing toward
the bottom of the diagram. The base lead is on the other side,
in the middle and is connected to the 4 turn loop. The collector
lead is at the top, and is connected to three things: the .01 uF
capacitor and both the 270k and 2.2k resistors. You can see which
lead is which on the BC547 transistor as follows. Go to this site:
http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC547.shtml
click on "Download BC547 datasheet from Fairchild Semiconductor"

Ed
 
On Tue, 05 Feb 2008 23:15:14 -0800, Dave.H wrote:

I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.
Click to expand...
If you knew the exact inductance, you could get a precision (Expensive!)
capacitor to tune it to 1431 KHz, but it's much easier to just use a
variable capacitor and lock the knob once you have it tuned.
 
On Feb 6, 6:44 am, ehsjr <eh...@bellatlantic.net> wrote:
Dave.H wrote:

snip



Sorry for all the questions, but would a couple of BC547 transistors
work instead of the 2N2222 one shown in the picture? I can get
2N2222A but I'm not sure if they're compatible with 2N2222, due to the
similar names I'm guessing they are.

This looks like a fun project for you. Enjoy experimenting with it
and feel free about asking questions.

Yes, you can use the BC547 or the 2N2222A or most any small
NPN transistor. Be sure to get the leads right when you
connect them to the circuit. In the schematic, the transistor
is drawn with an arrow in the emitter lead pointing toward
the bottom of the diagram. The base lead is on the other side,
in the middle and is connected to the 4 turn loop. The collector
lead is at the top, and is connected to three things: the .01 uF
capacitor and both the 270k and 2.2k resistors. You can see which
lead is which on the BC547 transistor as follows. Go to this site:http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC547.shtml
click on "Download BC547 datasheet from Fairchild Semiconductor"

Ed
Click to expand...
I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.
 
On Feb 6, 6:41 pm, "Stephen J. Rush" <sjr...@comcast.net> wrote:
On Tue, 05 Feb 2008 23:15:14 -0800, Dave.H wrote:
I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.

If you knew the exact inductance, you could get a precision (Expensive!)
capacitor to tune it to 1431 KHz, but it's much easier to just use a
variable capacitor and lock the knob once you have it tuned.
Click to expand...
I would do that but the capacitor doesn't tune to 1431 kHz.
 
On Feb 6, 4:37�am, "Dave.H" <the19...@googlemail.com> wrote:
I would do that but the capacitor doesn't tune to 1431 kHz.
==========================================
Click to expand...
If it wont tune lo enough, add a cap in parallel with the variable cap
 
On Tue, 05 Feb 2008 23:15:14 -0800, Dave.H wrote:

On Feb 6, 6:44 am, ehsjr <eh...@bellatlantic.net> wrote:
Dave.H wrote:

snip



Sorry for all the questions, but would a couple of BC547 transistors
work instead of the 2N2222 one shown in the picture? I can get
2N2222A but I'm not sure if they're compatible with 2N2222, due to the
similar names I'm guessing they are.

This looks like a fun project for you. Enjoy experimenting with it
and feel free about asking questions.

Yes, you can use the BC547 or the 2N2222A or most any small
NPN transistor. Be sure to get the leads right when you
connect them to the circuit. In the schematic, the transistor
is drawn with an arrow in the emitter lead pointing toward
the bottom of the diagram. The base lead is on the other side,
in the middle and is connected to the 4 turn loop. The collector
lead is at the top, and is connected to three things: the .01 uF
capacitor and both the 270k and 2.2k resistors. You can see which
lead is which on the BC547 transistor as follows. Go to this site:http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC547.shtml
click on "Download BC547 datasheet from Fairchild Semiconductor"

Ed

I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.
Click to expand...
Are you sure that's not 1430 kHz? Last time I looked the stations were
on even 10k multiples.

Thanks,
Rich
 
On Feb 7, 11:02 am, Rich Grise <r...@example.net> wrote:
On Tue, 05 Feb 2008 23:15:14 -0800, Dave.H wrote:
On Feb 6, 6:44 am, ehsjr <eh...@bellatlantic.net> wrote:
Dave.H wrote:

snip

Sorry for all the questions, but would a couple of BC547 transistors
work instead of the 2N2222 one shown in the picture? I can get
2N2222A but I'm not sure if they're compatible with 2N2222, due to the
similar names I'm guessing they are.

This looks like a fun project for you. Enjoy experimenting with it
and feel free about asking questions.

Yes, you can use the BC547 or the 2N2222A or most any small
NPN transistor. Be sure to get the leads right when you
connect them to the circuit. In the schematic, the transistor
is drawn with an arrow in the emitter lead pointing toward
the bottom of the diagram. The base lead is on the other side,
in the middle and is connected to the 4 turn loop. The collector
lead is at the top, and is connected to three things: the .01 uF
capacitor and both the 270k and 2.2k resistors. You can see which
lead is which on the BC547 transistor as follows. Go to this site:http://www.datasheetcatalog.com/datasheets_pdf/B/C/5/4/BC547.shtml
click on "Download BC547 datasheet from Fairchild Semiconductor"

Ed

I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.

Are you sure that's not 1430 kHz? Last time I looked the stations were
on even 10k multiples.

Thanks,
Rich
Click to expand...
I think AM is in 9 kHz steps here in Australia. The digital display
on my Sangean clearly displays 1431 Khz.
 
On Wed, 06 Feb 2008 20:38:29 -0800, Dave.H wrote:
On Feb 7, 11:02 am, Rich Grise <r...@example.net> wrote:
On Tue, 05 Feb 2008 23:15:14 -0800, Dave.H wrote:
....
I want to install a fixed capacitor in place of the tuning cap, what
value will I need for 1431 kHz? This frequency is home to ABC Radio
National, which I enjoy listening to late at night.

Are you sure that's not 1430 kHz? Last time I looked the stations were
on even 10k multiples.

I think AM is in 9 kHz steps here in Australia. The digital display on
my Sangean clearly displays 1431 Khz.
Click to expand...
OK, I stand informed. :)

You can use a fixed cap, but you have to know the inductance of the coil
to figure out what cap to use to resonate. Even then, you'll probably
want a trimmer, to "zero in" on the station.

Tood Luck!
Rich
 
On Feb 5, 7:42 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Feb 5, 10:34 pm, Chris <cfoley1...@yahoo.com> wrote:





On Feb 5, 4:11 am, "Dave.H" <the19...@googlemail.com> wrote:

Not sure if this is the correct place to ask, but here goes... I've
found plans for a simple two transistor AM radio receiver, but I'm not
sure how the ferrite loop antenna is connected to the radio. I'm not
at all good with schematics, I can understand most of it except for
the ferrite antenna bit.  I would appreciate any help on this.

http://www.techlib.com/electronics/crystal.html#Simple2transistor

Hi, Dave.  If you look at the picture, you can see 4 turns of yellow
insulated wire around the loopstick.  As shown in the schematic, one
wire is connected to the base of the first transistor, and the other
is connected to the + end of the 47uF cap and the 270K ohm resistor.
You've also got two very thin magnet wires (one red, one blue in the
illustration) which go to the tuning capacitor.

The idea is, you make the 4 turns with your own wire around the
existing loopstick, which you've scrounged from a garage sale
transistor radio along with the tuning cap.  Be careful not to break
the wires coming from the loopstick -- use a tweezers and a lot of
care when you pull it.

Hope this has answered your question.  The radio shown is fairly
simple, and shouldn't be too difficult to build.  If you're going with
trying to build on a real piece of wood board, use pine instead of oak
(softer, easier to work and pound nails), and use brass nails (most
nails don't accept solder).  If you can find someone with a little
electronics experience to help a bit it should be easy.

Good luck
Chris

I'm building it in a plastic project box, for portability reasons.
Should a 60-160 pF tuning cap work in this radio? I'm also wondering
how to hook up a 1 kohm - 8 ohm audio transformer so I can use my iPod
earphones with it.  The transformer has three wires on one side, and
two on the other from what I can see in the picture.- Hide quoted text -

- Show quoted text -
Click to expand...
If you cannot fine the crystal ear-phone then you'll need to use the 8
ohm matching transformer. Connect the xformer to an additional BC547
and here's the connection

BATTERY
|
+-----+
| +-. ,-o
| )|( 8 OHM
.-. 1K )|( EAR PHONE
68-120k| | +-' '-o
| | |
'-' |
VOLUME || | |/
CONTROL -||---+---| BC547
|| |>
1 uF |
|
== GND


You can leave the centre tap of the xformer open and just use the 2
end pieces. Play with the restor value to get the best volume. But
then it won't be a 2 transistor AM radio any more!

Allen
 
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