If you spend a lot of time and effort building a tube amp, even a small simple one. Draw blood hacking out the aluminium chassis....
Everyone interested in electronics should build at least one piece of equipment containing valves. It makes you appreciate solid-state electronics all the more!
If you spend a lot of time and effort building a tube amp, even a small simple one. Draw blood hacking out the aluminium chassis....
Everyone interested in electronics should build at least one piece of equipment containing valves. It makes you appreciate solid-state electronics all the more!
Servicing some old instruments with vacuum tubes for the "high speed" signals when the new instruments had micro's gave me a great appreciation for solid state electronics. Scary thing was most of the vacuum tube and relay junk was used by the company that made a large percentage of the vaccines produced around that time. I expected they would have the most up to date and accurate equipment. Silly me.
I have several pieces of Hallicrafters equipment. The AC circuits are sketchy in some of them (using a chassis ground) and the tuning is kinda cantankerous, but up and running the warm glow of the the tubes and scent of warm electronics is pretty cool!
Oh heck... why not? Explore the innards of the Duo-Diode-Triode or even the Nonode! http://www.sm5cbw.se/tubes/symbols.htm
Frankly, I always got lost right around the common Triode.
There must be something about this time of year that gets me thinking about vacuum tubes.
Here's a single tube amplifier that uses a transformer to couple with the speaker. I am not completely sure what the transformer does, but it looks neat:
Several years ago, I purchased a one-tube regenerative receiver off of eBay, from the guy who made them. I bought it mostly for the aesthetics, since he did such a beautiful job. Here's a photo:
The only drawback to performance is that it requires high-impedance headphones, which are a little hard to come by these days. But I was able to find a pair on eBay and, with a longwire antenna in the attic, I was able to pick up a soccer game in Australia from here on the U.S West coast.
I love the one tube amp picture. Naked terminals carrying 100s of volts! Meh, never mind, you are not going to touch it. Right?
I'm kind of wondering where the input coupling capacitor and bias resistor/capacitor is though.
I am not completely sure what the transformer does...
Easy, a tube operates at high voltages, a hundred or a lot more. But low current, milliamps. Meanwhile speakers are driven by big currents at low voltages. Well, what do you need to transform power at a high voltage and low current to a low voltage at a high current? A transformer.
It's an exercise in impedance matching.
The one tube regen. receiver looks like the kind of thing I built when I was about 13. Before I got into TTL then microprocessors and such.
It was totally amazing to hear guys yaking from South America over in Blighty, on such a simple thing.
There must be something about this time of year that gets me thinking about vacuum tubes.
Here's a single tube amplifier that uses a transformer to couple with the speaker. I am not completely sure what the transformer does, but it looks neat:
No, it runs entirely on 12VDC. No "B" battery required. The tube, made by RCA, is a VT-136 pentode.
BTW, I tried everything I could think of to get this receiver to work without having to buy high-impedance headphones, including matching transformer to low-impedance phones, 2K termination resistor to amp input, etc. Nothing besides the high-impendance phones worked for me.
@Phil, that tube regen is a steampunk work of art. I love it.
Last winter I built a shortwave using a NE602 mixer IC and a long wire kit off of eBay for $20. But the NE602 is too much of a black box, so I've been thinking about building a tube regen ever since. But my job has been crazy which back burner-ed that and my robotics hobby.
I can't help thinking that with a maximum swing of 12 volts and almost no current available even a capacitively coupled 741 opamp would have made a good headphone amp.
Ah, the "B" batteries. Whatever happened to the 90v EverReady ?
my first exposure to electronics was with this Gilbert "Erec-tronic" kit:
With it, one could build a regenerative shortwave receiver. The regeneration was adjusted using a "tickler" coil inserted into the tuning coil form. It was called a tickler for good reason, too, as adjustment was extremely ticklish between an ear-piercing squeal and nothing at all. Of course, having one's hand anywhere near it changed both regeneration and tuning, so you had to set it, withdraw your hand, reset it, withdraw your hand, on-and-on, until it was just right.
I remember attempting to build a so-called "foxhole" radio. Instead of a commercial diode, rectification resulted from the contact between a piece of pencil lead wired to a safety pin and a Gillette "blue" razor blade:
The article and book cited in the above link, "How to Build a 'Foxhole Radio' ", from All About Radio and Television by Jack Gould, Random House, 1958, seem familiar and was probably the book I borrowed from the childrens' section of the local public library (the same childrens' section, BTW, that included a book on building gunpowder skyrockets).
I recall winding the coil around a toilet paper tube -- a tedious process that has forever since put me off of coil winding. 'Never could get the radio to work. 'Heard nothing but static as the pencil lead was scraped across the razor blade.
Despite such failure, I consider myself very lucky for having first experienced electronics so "close-to-the-metal." There are so many layers of abstraction separating today's hobbyists from reality that it's hard to imagine they can obtain a gut-level feeling for what they're doing. I had an attorney ask me once, "You do all this programming with microcontrollers and such, but do you really understand how they work?" I had to answer, "No, it's more just a leap of faith (à la Kierkegaard) in the abstraction layers that gets me from code and 'registers' and 'execution' to reality."
Wow, that pic brings back memories! Back when my age was expressed with a single decimal digit, practically every project started the same way: A plank of 3/4" pine and my dad's cross-cut saw. Then out came the sander, shellac, and Fahnestock clips. Sooner or later, friction tape would be involved. Such great memories. Such great smells.
Edit:
Nowadays, projects usually begin with a used cardboard box, a table saw, and hot glue. It's all going in the dumpster as soon as I'm dead, anyway.
@Phil, I built several crystal radios when I was a teen. I tried to convert them to foxhole radios and never got them to work either. Probably being in a foxhole gives you the proper time and motivation to get the point contact diode working.
Here's a two tube resistively coupled amp that does away with the transformer
I'm guessing that foxhole radio is extremely dependant on the proper earphones, as the only power is the transmitter, so they would have to be sensitive.
AWESOME stuff here guys. I love radios of all types and have built many since my formative years in ham radio. SWL is still jolly good fun. One of my favorite radios is a vintage regenerative Heathkit GR-10 I rescued from the TRW swap meet.
I live ~ 2 miles from AM radio station KNX 1070: 50,000 watts and 3 mammoth vertical antennas. I can pick up news & traffic report on most any circuit I build. Funny what passes for a rectifier when you're not even trying.
I live ~ 2 miles from AM radio station KNX 1070: 50,000 watts and 3 mammoth vertical antennas. I can pick up news & traffic report on most any circuit I build. Funny what passes for a rectifier when you're not even trying.
With that power and proximity, I could probably pick it up with the fillings in my teeth!
The Morgan book with the schematics is "The boys' first book of radio and electronics" but it has been out of print for 50 years. Used copies sell for insane amounts which is really sad.
The Morgan book with the schematics is "The boys' first book of radio and electronics" but it has been out of print for 50 years. Used copies sell for insane amounts which is really sad.
I got my start in things reading all of his books, but not trying out any of them. Then I discovered TTL and CMOS families, and of course microprocessors.
Now I'm looking at the gadgetry that our hosts sell.
Strange.... What are nearly all of your robots doing here, erco?
Comments
Everyone interested in electronics should build at least one piece of equipment containing valves. It makes you appreciate solid-state electronics all the more!
Servicing some old instruments with vacuum tubes for the "high speed" signals when the new instruments had micro's gave me a great appreciation for solid state electronics. Scary thing was most of the vacuum tube and relay junk was used by the company that made a large percentage of the vaccines produced around that time. I expected they would have the most up to date and accurate equipment. Silly me.
Amanda
Oh heck... why not? Explore the innards of the Duo-Diode-Triode or even the Nonode! http://www.sm5cbw.se/tubes/symbols.htm
Frankly, I always got lost right around the common Triode.
@
Like the Large Hadron Collider:
http://home.cern/topics/large-hadron-collider
I'm not sure but I bet they have heaters at the source of protons in there somewhere.
I have a few 6.3 VAC transformers I can send them.
Here's a single tube amplifier that uses a transformer to couple with the speaker. I am not completely sure what the transformer does, but it looks neat:
http://www.timefracture.org/radiopics/onetubeamp.jpg
http://www.timefracture.org/radiopics/regenrear2.jpg
The only drawback to performance is that it requires high-impedance headphones, which are a little hard to come by these days. But I was able to find a pair on eBay and, with a longwire antenna in the attic, I was able to pick up a soccer game in Australia from here on the U.S West coast.
-Phil
He done a nice job of making it look of the tube era, pretty dovetailed cabinet. would that be a high voltage anode?
I love the one tube amp picture. Naked terminals carrying 100s of volts! Meh, never mind, you are not going to touch it. Right?
I'm kind of wondering where the input coupling capacitor and bias resistor/capacitor is though. Easy, a tube operates at high voltages, a hundred or a lot more. But low current, milliamps. Meanwhile speakers are driven by big currents at low voltages. Well, what do you need to transform power at a high voltage and low current to a low voltage at a high current? A transformer.
It's an exercise in impedance matching.
The one tube regen. receiver looks like the kind of thing I built when I was about 13. Before I got into TTL then microprocessors and such.
It was totally amazing to hear guys yaking from South America over in Blighty, on such a simple thing.
Impedance matching the tube high voltage low current output to the speaker/headphone low voltage high current requirement.
Edit - Plus removing the dc component of the tube signal of course.
No, it runs entirely on 12VDC. No "B" battery required. The tube, made by RCA, is a VT-136 pentode.
BTW, I tried everything I could think of to get this receiver to work without having to buy high-impedance headphones, including matching transformer to low-impedance phones, 2K termination resistor to amp input, etc. Nothing besides the high-impendance phones worked for me.
-Phil
Last winter I built a shortwave using a NE602 mixer IC and a long wire kit off of eBay for $20. But the NE602 is too much of a black box, so I've been thinking about building a tube regen ever since. But my job has been crazy which back burner-ed that and my robotics hobby.
Ah, the "B" batteries. Whatever happened to the 90v EverReady ?
my first exposure to electronics was with this Gilbert "Erec-tronic" kit:
With it, one could build a regenerative shortwave receiver. The regeneration was adjusted using a "tickler" coil inserted into the tuning coil form. It was called a tickler for good reason, too, as adjustment was extremely ticklish between an ear-piercing squeal and nothing at all. Of course, having one's hand anywhere near it changed both regeneration and tuning, so you had to set it, withdraw your hand, reset it, withdraw your hand, on-and-on, until it was just right.
And it included a "B" battery (45V).
-Phil
They are beautiful.
I got my start aged 9 or 10 with a Philips Electronic Engineer Kit
The crystal radio I had to build with my dad, winding a coil around a sawn up broom handle and using an OA71 germanium diode.
Then came the tubes.
Then came TTL.
Then came the micro-processor.
After that it's all a blur...
Until, then there was the Propeller !
The article and book cited in the above link, "How to Build a 'Foxhole Radio' ", from All About Radio and Television by Jack Gould, Random House, 1958, seem familiar and was probably the book I borrowed from the childrens' section of the local public library (the same childrens' section, BTW, that included a book on building gunpowder skyrockets).
I recall winding the coil around a toilet paper tube -- a tedious process that has forever since put me off of coil winding. 'Never could get the radio to work. 'Heard nothing but static as the pencil lead was scraped across the razor blade.
Despite such failure, I consider myself very lucky for having first experienced electronics so "close-to-the-metal." There are so many layers of abstraction separating today's hobbyists from reality that it's hard to imagine they can obtain a gut-level feeling for what they're doing. I had an attorney ask me once, "You do all this programming with microcontrollers and such, but do you really understand how they work?" I had to answer, "No, it's more just a leap of faith (à la Kierkegaard) in the abstraction layers that gets me from code and 'registers' and 'execution' to reality."
-Phil
Wow, that pic brings back memories! Back when my age was expressed with a single decimal digit, practically every project started the same way: A plank of 3/4" pine and my dad's cross-cut saw. Then out came the sander, shellac, and Fahnestock clips. Sooner or later, friction tape would be involved. Such great memories. Such great smells.
Edit:
Nowadays, projects usually begin with a used cardboard box, a table saw, and hot glue. It's all going in the dumpster as soon as I'm dead, anyway.
Here's a two tube resistively coupled amp that does away with the transformer
http://va3ngc.weebly.com/blog/morgan-2-tube-resistance-coupled-amp
Which confuses me because if the tubes are high voltage low current, how does adding a second solve the impedance mismatch?
The second stage might be a cathode follower, which provides a low impedance -- like an emitter follower does in a transistor amplifier.
-Phil
I live ~ 2 miles from AM radio station KNX 1070: 50,000 watts and 3 mammoth vertical antennas. I can pick up news & traffic report on most any circuit I build. Funny what passes for a rectifier when you're not even trying.
With that power and proximity, I could probably pick it up with the fillings in my teeth!
-Phil
But wow, I found this http://danielwebb.us/projects/pd_tech_books/the_boy_electrician.pdf
An earlier book by Morgan on electricity and stuff. A Must read for anyone playing with electrons.
Ha... I have a great face for radio and you have the mouth for it!
My first electronics book (still have it!) was "Elements of Radio". Still commonly available and affordable on Ebay.
I got my start in things reading all of his books, but not trying out any of them. Then I discovered TTL and CMOS families, and of course microprocessors.
Now I'm looking at the gadgetry that our hosts sell.
Strange.... What are nearly all of your robots doing here, erco?