In practice, the detector tuning capacitor, the antenna tuning capacitors and the amount of coupling between the two coils are all juggled until the strongest signal is obtained. For most crystal sets a simple 365pF variable capacitor will work fine. They are available on eBay other sources.
For most crystal sets a simple 365pF variable capacitor will work fine. They are available on eBay other sources. The single section capacitor is typically used for the detector, while a dual section capacitor is typically used with its sections in parallel for the antenna circuit.
Capacitor C2 is used to match the antenna system, and C3 is the main tuning capacitor. Absent from this circuit is the finicky ga-lena-and-catwisker detector. It has been supplanted by a 1N34 germanium diode that is connected near the grounded end of the tuned circuit that includes coil L1. C1 is an RF bypass capacitor.
Typical High-Z crystal earpiece. The Length-to-Diameter Ratio of a coil can affect the Q of a single-layer close-wound coil. A high Q insures improved circuit efficiency, a narrower bandwidth and less wide-band noise in oscillator circuits. (Thus better selectivity or the ability to separate stations.)
Air is best, there should be no metal near the coil. The Length-to-Diameter Ratio should not exceed 4:1. Ratios of between 1:1 and 2:1 are preferred for most circuits. Note the AM Broadcast (U.S.) 535-1705 kHz. We need 229uH coil to work with a 500 pf variable cap based on various formulas I used on the 1930s coil.
Coil Q is a very important consideration when designing a crystal set. The selectivity of your completed crystal set (its ability to separate close adjacent stations) will be determined primarily by the Q of the detector coil, and to a lesser extent by the Q of the antenna coil.
The coil is an inductor and is measured in the unit Henry (H). A simple coil consists of an iron core wrapped with the copper wire. If a DC voltage is applied to a coil, the …
The second coil used a 2 inch diameter cardboard tube and 75 turns on the main coil and again 25 turns for the secondary. The tuning capacitor was an antique unit from a five tube table …
I''ve been looking at crystal radios recently, and I noticed that many of them had quite big coils (maybe around 5cm on average from what I …
This will generally consist of a coil and a capacitor forming a tuned circuit. Either the capacitor or inductor, or both need to be variable so circuit can be tuned to different stations. The classic values are 250 uH and 365 pF to tune the …
I''ve been looking at crystal radios recently, and I noticed that many of them had quite big coils (maybe around 5cm on average from what I can see), but wouldn''t they want …
Capacitor C2 is used to match the antenna system, and C3 is the main tuning capacitor. Absent from this circuit is the finicky ga-lena-and-catwisker detector. It has been supplanted by a …
Connecting the Crystal Radio Coil is simple, and as you can see from the diagram above, the coil has only two terminals. One side is the antenna side, which is where one would connect an …
1 Crystal Set Design 102 Al Klase 11 Crystal Radio Antennas Owen Poole 31 Crystal Radio DXing Steve McDonald 45 The Crystal Radio Revisited Smith-Kettlewell ... coil, a variable …
This may also be an appropriate time to hook up the aerial and ground wires and find a suitable variable capacitor. Simply connect the ferrite coil as shown in the circuit diagram. For this …
The antenna tuner is a straightforward tank circuit with a ganged antenna capacitor. Trimmers were added to allow dial calibration and compensation for different antennas. To calibrate, I …
The tuned circuits in a crystal radio are composed of a coil (inductor) and a capacitor, usually variable, to allow tuning the circuit to the desired frequency. A crystal set can be made with a …
This is actually not a bad crystal set, and it contains a coil, a variable capacitor, a germanium diode, and, most importantly, a reasonably sensitive high-impedance ear phone. You''re also …
The multi section coils are usually ''tapped'', which means additional wires are connected to the sections and run to pins on the base of the coil. This allows the use of a multi-position switch …
This is actually not a bad crystal set, and it contains a coil, a variable capacitor, a germanium diode, and, most importantly, a reasonably sensitive high-impedance ear phone. You''re also going to need an antenna.
The second coil used a 2 inch diameter cardboard tube and 75 turns on the main coil and …
Making a crystal radio is a fun and relatively simple project that allows you to listen to nearby AM radio stations. ... paper and paper towel rolls, masking tape, screws, wires, …
As shown, secondary coil along with capacitor C1 will form series resonance circuit. When this circuit is tuned to resonance, high voltage will get produced across capacitor. This is referred …
Use a smaller coil form to approximate a 1:1 length-diameter ratio. Use a smaller inductance value (same as L2?) for L1. This is by no means a complete list of the things that can be tried with this circuit. In fact, I even redesigned the coil to …
Note: The coil in the picture has an additional 10 turn winding that is intended to be a tickler coil to turn the crystal set into a regenerative receiver. The extra winding has also ... The air-variable …
Capacitor C2 is used to match the antenna system, and C3 is the main tuning capacitor. …
two coils (each generally resonated with a capacitor) lightly coupled to each other. • One coil is connected to the antenna, the other is connected to the detector. • Even cheap capacitors …
The tuned circuits in a crystal radio are composed of a coil (inductor) and a capacitor, usually variable, to allow tuning the circuit to the desired frequency. A crystal set can be made with a single tuned circuit (the detector coil), or with …
The antenna tuner is a straightforward tank circuit with a ganged antenna capacitor. Trimmers were added to allow dial calibration and compensation for …
The desired signsl is selected by tuned circuit C1a-L2 and coupled through capacitor C2 to a second tuned circuit C1b-L3, which improves the selectivity by narrowing the r.f. bandpass. …
Use a smaller coil form to approximate a 1:1 length-diameter ratio. Use a smaller inductance value (same as L2?) for L1. This is by no means a complete list of the things that can be tried …