copper oxide also makes a decent rectifier, good one is across a small dc motor, the bushes naturally form oxide in use and it makes a reasonable detector
Really cool, could any oxyded copper work ? I'm thinking of copper tubing for water or copper coins ? (I tried the "burned" razorbl@de and pencil "wisk" diode years ago, couldn't make it work 😅)
@@weistonaski6924 I am not totally sure, there is more than one copper oxide, but before semiconductors the prefered type of rectifier for any sort of power was copper oxide, there is a fair bit of literature around about it. Generally any metal oxide will rectify a certain amount (this is where the rusty razor blade comes in as well), some better than others. And then there is the amplifying oxides, like Zincite.
Should also do a lead pencil resistor and a single battery (or a calculator solar cell) to bias up the diode to overcome the bandgap and use any diode for good results.
@@fotografm ， the piezoelectric earbud is a pure capacitor. Once it’s charged up the diagram moves to push the air to produce the first sound. Then it will not reset the position to make the next sound unless you gave the 200k as a dc path to let the charges discharge .
I don't see any reason why it would, capacitance is capacitance. As long as there is no resistance across the cap introduced, which would diminish the coil Q factor. Where gains might be made is improving the coil Q factor, or by adding even a short length of external antenna and/or ground (this is based on personal experience). The easy one that stands out in my mind is to find an earth to connect the bottom end of the coil and capacitor to (any metal goignto the ground you can electically connect to, eg street sign or bike rack that is not painted or has some bolt exposed), this could make a big difference to volume and sensititvity.
One of the reasons I'm so pissed because growing up in school they did not teach this is common knowledge they didn't show us instead they hid it away to be rediscovered later
copper oxide also makes a decent rectifier, good one is across a small dc motor, the bushes naturally form oxide in use and it makes a reasonable detector
Really cool, could any oxyded copper work ? I'm thinking of copper tubing for water or copper coins ? (I tried the "burned" razorbl@de and pencil "wisk" diode years ago, couldn't make it work 😅)
@@weistonaski6924 I am not totally sure, there is more than one copper oxide, but before semiconductors the prefered type of rectifier for any sort of power was copper oxide, there is a fair bit of literature around about it.
Generally any metal oxide will rectify a certain amount (this is where the rusty razor blade comes in as well), some better than others.
And then there is the amplifying oxides, like Zincite.
Should also do a lead pencil resistor and a single battery (or a calculator solar cell) to bias up the diode to overcome the bandgap and use any diode for good results.
You sound like Burt Kwouk.
Great portable crystal radio.
Excellent idea ! What was the point of the 200k resistor ?
@@fotografm ， the piezoelectric earbud is a pure capacitor. Once it’s charged up the diagram moves to push the air to produce the first sound. Then it will not reset the position to make the next sound unless you gave the 200k as a dc path to let the charges discharge .
@@BillyCdiy Aha ! I thought it might be something to do with providing a path for DC but had not thought about the capacitive effect of the earpiece !
Hi Billy, will the Crystal set be even more sensitive if an air variable capacitor was used?
@@javiermac381 , yes I agree.
Thanks Billy, you are the Greatest! 📻😁
I don't see any reason why it would, capacitance is capacitance. As long as there is no resistance across the cap introduced, which would diminish the coil Q factor.
Where gains might be made is improving the coil Q factor, or by adding even a short length of external antenna and/or ground (this is based on personal experience).
The easy one that stands out in my mind is to find an earth to connect the bottom end of the coil and capacitor to (any metal goignto the ground you can electically connect to, eg street sign or bike rack that is not painted or has some bolt exposed), this could make a big difference to volume and sensititvity.
One of the reasons I'm so pissed because growing up in school they did not teach this is common knowledge they didn't show us instead they hid it away to be rediscovered later
amazing, i would do this if i was homeless. 10/10