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Sorry forgot the linkI'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
I have a variable capacitor in a junker 5 valve radio from the '60's.On Dec 12, 8:43 pm, "Dave.H" <the19...@googlemail.com> wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Sorry forgot the linkhttp://scitoys.com/scitoys/scitoys/radio/ten_minute_radio.html
The 60-120pf will work. It will just tune a narrower range of frequencies.On Dec 12, 8:52 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Dec 12, 8:43 pm, "Dave.H" <the19...@googlemail.com> wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Sorry forgot the linkhttp://scitoys.com/scitoys/scitoys/radio/ten_minute_radio.html
I have a variable capacitor in a junker 5 valve radio from the '60's.
This is marked 2 1215 What value would this be, how would I be able to
measure it, there's 4 terminals two have got green wires, one with
two, haven't followed them to see where they go, another terminal has
a ceramic cap to chassis ground, the other isn't used.
I don't want it to tune a narrower range of frequencies, maybe IOn Wed, 12 Dec 2007 02:03:28 -0800 (PST), "Dave.H" <the19...@googlemail.com> wrote:
On Dec 12, 8:52 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Dec 12, 8:43 pm, "Dave.H" <the19...@googlemail.com> wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Sorry forgot the linkhttp://scitoys.com/scitoys/scitoys/radio/ten_minute_radio.html
I have a variable capacitor in a junker 5 valve radio from the '60's.
This is marked 2 1215 What value would this be, how would I be able to
measure it, there's 4 terminals two have got green wires, one with
two, haven't followed them to see where they go, another terminal has
a ceramic cap to chassis ground, the other isn't used.
The 60-120pf will work. It will just tune a narrower range of frequencies.
Most of the old tuning caps were 2 section units. One used for the oscillator
and one for input tuning. The input tuning section was larger and should be in the
20-365pf range. I don't remember the typical values for the oscillator section,
but it was lower. Some had three sections and used 2 sections for input tuning.
The easiest way to measure it is to borrow a capacitance meter. Otherwise
a you'll need a calibrated signal generator (or generator and frequency counter)
and an oscilloscope to measure the tuning range, or maybe a grid dip meter.
If you can find an old transistor radio just take both the ferrite antenna and
cap from it and use them together. Don't expect too much from it and be sure you
have a good ground. Make sure the earphone is right type. A low impedance type
will not work well if at all.
Mike
When truth is absent politics will fill the gap.
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
will come through.On Dec 12, 10:21 pm, Mike <nomtrxs...@comcast.net> wrote:
On Wed, 12 Dec 2007 02:03:28 -0800 (PST), "Dave.H" <the19...@googlemail.com> wrote:
On Dec 12, 8:52 pm, "Dave.H" <the19...@googlemail.com> wrote:
On Dec 12, 8:43 pm, "Dave.H" <the19...@googlemail.com> wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Sorry forgot the linkhttp://scitoys.com/scitoys/scitoys/radio/ten_minute_radio.html
I have a variable capacitor in a junker 5 valve radio from the '60's.
This is marked 2 1215 What value would this be, how would I be able to
measure it, there's 4 terminals two have got green wires, one with
two, haven't followed them to see where they go, another terminal has
a ceramic cap to chassis ground, the other isn't used.
The 60-120pf will work. It will just tune a narrower range of frequencies.
Most of the old tuning caps were 2 section units. One used for the oscillator
and one for input tuning. The input tuning section was larger and should be in the
20-365pf range. I don't remember the typical values for the oscillator section,
but it was lower. Some had three sections and used 2 sections for input tuning.
The easiest way to measure it is to borrow a capacitance meter. Otherwise
a you'll need a calibrated signal generator (or generator and frequency counter)
and an oscilloscope to measure the tuning range, or maybe a grid dip meter.
If you can find an old transistor radio just take both the ferrite antenna and
cap from it and use them together. Don't expect too much from it and be sure you
have a good ground. Make sure the earphone is right type. A low impedance type
will not work well if at all.
Mike
When truth is absent politics will fill the gap.
I don't want it to tune a narrower range of frequencies, maybe I
should try the old capacitor I have
In practice I think you will find that only 198KHz, Radio 4 signal
Yes, with a narrower tuning range. But you can addI'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Thanks for all your help, I've found a better crystal radio diagram onDave.H wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Yes, with a narrower tuning range. But you can add
switched fixed value capacitors to extend the range,
if you want. This is a kludgy arrangement, but will
get you the full tuning range:
S1 S2
--------+-----o o---+---o o---+
| \ | \ |
[C1] [C2] [C3]
| | |
--------+------------+----------+
Values:
C1 60-160 pf variable
C2 56 pf fixed
C3 30 pf fixed
Range(pf) S1 S2
29-41 Closed Open
36-68 Closed Closed
60-160 Open Open
The site you posted sells a variable cap for use in
their radios - that may be a better choice than
using the switch capacitor kludge.
Ed
How many turns of wire would I need to get a value of 230 mH using a aOn Dec 13, 5:08 pm, ehsjr <eh...@bellatlantic.net> wrote:
Dave.H wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Yes, with a narrower tuning range. But you can add
switched fixed value capacitors to extend the range,
if you want. This is a kludgy arrangement, but will
get you the full tuning range:
S1 S2
--------+-----o o---+---o o---+
| \ | \ |
[C1] [C2] [C3]
| | |
--------+------------+----------+
Values:
C1 60-160 pf variable
C2 56 pf fixed
C3 30 pf fixed
Range(pf) S1 S2
29-41 Closed Open
36-68 Closed Closed
60-160 Open Open
The site you posted sells a variable cap for use in
their radios - that may be a better choice than
using the switch capacitor kludge.
Ed
Thanks for all your help, I've found a better crystal radio diagram on
the internet, where I get to wind my own coil, something I wouldn't
mind trying, and I've found a source for the parts.
Sorry that should be 230 uH.On Dec 14, 12:30 am, "Dave.H" <the19...@googlemail.com> wrote:
On Dec 13, 5:08 pm, ehsjr <eh...@bellatlantic.net> wrote:
Dave.H wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Yes, with a narrower tuning range. But you can add
switched fixed value capacitors to extend the range,
if you want. This is a kludgy arrangement, but will
get you the full tuning range:
S1 S2
--------+-----o o---+---o o---+
| \ | \ |
[C1] [C2] [C3]
| | |
--------+------------+----------+
Values:
C1 60-160 pf variable
C2 56 pf fixed
C3 30 pf fixed
Range(pf) S1 S2
29-41 Closed Open
36-68 Closed Closed
60-160 Open Open
The site you posted sells a variable cap for use in
their radios - that may be a better choice than
using the switch capacitor kludge.
Ed
Thanks for all your help, I've found a better crystal radio diagram on
the internet, where I get to wind my own coil, something I wouldn't
mind trying, and I've found a source for the parts.
How many turns of wire would I need to get a value of 230 mH using a a
carboard tube from a toilet or paper towel roll? The site I've linked
to in this message has some calculations, but I never was good at
maths.
http://my.integritynet.com.au/purdic/crystal_set.htm
Somewhere around 100T of #24.How many turns of wire would I need to get a value of 230 mH using a a
carboard tube from a toilet or paper towel roll? The site I've linked
to in this message has some calculations, but I never was good at
maths.
http://my.integritynet.com.au/purdic/crystal_set.htm
Sorry that should be 230 uH.
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
When I went to school, the values of capacitors in parallel added, soDave.H wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Yes, with a narrower tuning range. But you can add
switched fixed value capacitors to extend the range,
if you want. This is a kludgy arrangement, but will
get you the full tuning range:
S1 S2
--------+-----o o---+---o o---+
| \ | \ |
[C1] [C2] [C3]
| | |
--------+------------+----------+
Values:
C1 60-160 pf variable
C2 56 pf fixed
C3 30 pf fixed
Range(pf) S1 S2
29-41 Closed Open
36-68 Closed Closed
60-160 Open Open
Yup, me too. I drew it wrong. The intent was to haveOn Thu, 13 Dec 2007 06:08:45 GMT, ehsjr <ehsjr@bellatlantic.net
wrote:
Dave.H wrote:
I'm planning to build a crystal radio similar to the one linked to at
the bottom of this post, but the specs call for a 30-160 pf tuning
capacitor, all I can find is a 60-160 pf cap. Will this still work?
Yes, with a narrower tuning range. But you can add
switched fixed value capacitors to extend the range,
if you want. This is a kludgy arrangement, but will
get you the full tuning range:
S1 S2
--------+-----o o---+---o o---+
| \ | \ |
[C1] [C2] [C3]
| | |
--------+------------+----------+
Values:
C1 60-160 pf variable
C2 56 pf fixed
C3 30 pf fixed
Range(pf) S1 S2
29-41 Closed Open
36-68 Closed Closed
60-160 Open Open
When I went to school, the values of capacitors in parallel added, so
the ranges would be (bottom up, on your table) 60 - 160pF, 116 -
216pF, and 146 - 246pF.
and wind some manageable magnet wire around it, maybe #32-#36; close-snip
How many turns of wire would I need to get a value of 230 mH using a a
carboard tube from a toilet or paper towel roll? The site I've linked
to in this message has some calculations, but I never was good at
maths.
http://my.integritynet.com.au/purdic/crystal_set.htm
Sorry that should be 230 uH.
Somewhere around 100T of #24.
Try http://www.lalena.com/Audio/Calculator/Inductor/ or google for an
inductor calculator if you don't like that one.
Your best bet would be to wind maybe 130T turns and addd taps every 10T
starting at about 70T, or unwind turns until you get the right tuning
range.
If you add more taps, who knows, you might pickup some shortwave
depending on antenna, ground, and receiving conditions in your area.
When I was a Boy Scout, we would make variable inductors. Take a TP roll,