Making a transistor

[Modelworks]

I was thinking about time travel and what if you went back to say 1800, what kind of technology could I give them then that would effect the future the most.

I was thinking radio at first.
AM radio could be done fairly easily.
Then a friend got in the discussion and I ended up in a bet.
He decided AM was too easy and so the challenge is FM.
I want to create a basic FM receiver with nothing but the technology available at the time.

This means constructing all parts from only items that would have been available in the year 1800. No bringing diodes, etc from the future

Resistors - could use charcoal and paper
Capacitors - paper and thin metal, or glass and metal
Diodes - steel and graphite
Battery power - lead, sulfuric acid, zinc,cadmium
Speaker - paper, wire, magnet.

Transistors - undecided.

I know I could go the tube route but I would rather not.

If I can build the receiver then I want to move on to creating a transmitter.

So any ideas on creating a transistor with year 1800 tech ?

 

[bobsmith1492]

Bake some sand, dope it with some dope?

 

[BrownTown]

use vacuum tubes instead?

really, either way your screwed, you can make some sort of diode and resistor and maybe transistor and stuff, but there is no way your gonna be able to size them right, it would just be a crap shoot to get any sort of functional device.

 

[degibson]

Well, the real problem would be getting dopant into the silicon (if you even used silicon... other semis might be better/easier). Contacts should be reasonable, and getting the semi itself would be possible, though you'd have to do some chemistry to determine if it was the right stuff (after all, semiconductors weren't specially classified at the time).

Doping would be quite difficult however -- today, dopants are added by adding so much energy to the dopant (heating) that the dopant molecules have enough energy to diffuse into the silicon. Its not that the 1800s couldn't provide the heat, but I think you'd have a very hard time attaining macroscopic diffusion. Today's technique works because diffusion doesn't need to be very deep, as the transistors themselves are so small.

Tubes seem like an excellent alternative here. Considering you'll have practically no electrical tools or resources (e.g. no current sources, voltage regs, just rudimentary chemical batteries and generators). The light bulb is already contemporary, so the technology is around at least to make vacuum tubes.

 

[Born2bwire]

You can make vacuum tubes by hand. I would go that route.

 

[dkozloski]

You can tune an FM signal with an AM detector by using slope detection. A simple crystal receiver tuned off the center of the FM transmitted signal will give you a usuable output. As the FM signal moves closer and farther away from the bandpass of the crystal tuner it appears to be an AM signal to the tuner. No need to invent the wheel. The only exotic thing you're going to need is a needle and a galena crystal.

 

[Born2bwire]

Originally posted by: dkozloski
You can tune an FM signal with an AM detector by using slope detection. A simple crystal receiver tuned off the center of the FM transmitted signal will give you a usuable output. As the FM signal moves closer and farther away from the bandpass of the crystal tuner it appears to be an AM signal to the tuner. No need to invent the wheel. The only exotic thing you're going to need is a needle and a galena crystal.

Or he could use a razor blade for his crystal. Although, razor blades weren't introduced until the early 1900's. There also is a suggestion to use coke (coal) or make a simple diode.

http://bizarrelabs.com/foxhole.htm

 

[wwswimming]

Originally posted by: Modelworks
I was thinking about time travel and what if you went back to say 1800, what kind of technology could I give them then that would effect the future the most.

I was thinking radio at first.

i think feminine hygiene products, in lieu of whatever may have
been used at the time { rags or seagull feathers ? }, might prove
to be quite popular.

also if i was in the year 1800, i would need a work-around to
1800 dentistry.

if you could time travel, it would probably be like space travel,
where you work with government agencies. sort of like NASA,
except NASTA.

is this like at the beginning of Terminator 2, you have to got
through naked ? can't even take any 747 opamps with you ?

AM radio could be done fairly easily.
Then a friend got in the discussion and I ended up in a bet.
He decided AM was too easy and so the challenge is FM.
I want to create a basic FM receiver with nothing but the technology available at the time.

This means constructing all parts from only items that would have been available in the year 1800. No bringing diodes, etc from the future

Resistors - could use charcoal and paper

done that, it works.

capacitors - paper and thin metal

american money paper and gold leaf. maybe with an electrolyte.

doesn't it involve melting silicon ? maybe convince a blacksmith to
melt some sand for you, then stir in some arsenic or whatever to
change the PN characteristics. what are the choices ? whatever
rocks, minerals, & metals you can find that you can melt that are
miscible with the silicon.

then you break that up into pieces and hook it up to the battery.

is this a rogue operation or are you going back with the approval of
a government agency ? if i was an inter time travel agent, i'd ask
for permission to bring a laptop and a printer and a solar cell.

 

[Cogman]

Do some research on how the first transistor was made would probably be your best bet (used gallenium?) But ultimately vacuum tubes might be easier.

Are you going to be able to use semi modern tech to measure things? Because measuring the resistance of your resistors and the capacitance of your capacitors is going to be a real challenge with 1800 tech.

Good luck though, and let us know the route you take. I find this stuff very interesting (Expects Terminator like nuking, but will be prepared to make my own computer and electricity )

 

[Modelworks]

Thanks for the suggestions.
Measuring the values of the components was a part of the equation I had forgotten.
Making a voltmeter isn't really a problem, so I guess I will start there.
A voltmeter will allow me to measure all the other components.


Capacitors I have built before for a laser power supply, used 2ft square glass, 1/8" thick, alternating with thin copper plate, 32 layers.
I guess the transistor might be out, vacuum tubes are doable, I have access to a vacuum pump.

Diode will be a point contact method, rusted steel + graphite.


The ground rules are that the only thing you can take back to 1800 is knowledge, so I'll start with the meter tomorrow.

 

[Born2bwire]

Originally posted by: Modelworks
Thanks for the suggestions.
Measuring the values of the components was a part of the equation I had forgotten.
Making a voltmeter isn't really a problem, so I guess I will start there.
A voltmeter will allow me to measure all the other components.


Capacitors I have built before for a laser power supply, used 2ft square glass, 1/8" thick, alternating with thin copper plate, 32 layers.
I guess the transistor might be out, vacuum tubes are doable, I have access to a vacuum pump.

Diode will be a point contact method, rusted steel + graphite.


The ground rules are that the only thing you can take back to 1800 is knowledge, so I'll start with the meter tomorrow.

I think the next problem is going to be a transmitter, mainly how to create an AC source. Don't know offhand how you would do this but I would suggest taking a look at some of Hertz's work with spark gap generators. He's the one that really started it all.

 

[QuixoticOne]

Go sit in the parking lot of a decently powerful FM transmitter antenna site, preferably
one without any / too many other co-located antennas on other frequencies / services (this is the hard part).

It'll be hard NOT to receive the signal on any old thing....dental fillings, toaster, whatever.

If you're trying to receive an existing powerful commercial broadcast that's cheating a bit since they wouldn't have easily had 50,000 Watt average output power transmitters for many years to come even using tubes on any similar VHF frequency. Nevertheless, a receiver would be a neat thing to build, and the challenge would be increased due to the fact that there are many closely spaced stations to deal with, and the fact that they're broadband services with analog, digital, stereo, et. al. which all sort of confound a bit making a simple audio baseband decoder.

If you're making a transmitter / receiver pair then in some ways it is easier since you can design them to match expedience of construction as well as to match each other fairly easily.

There are various unlicensed / loosely licensed (for low power equpment or various other restrictions) frequencies you could check into using to experiment with, all the way from down around 100kHz up past 915 MHz, past the 2.45GHz used for most wireless LANs, including some around 5.8GHz. Of course if you want to be able to generate significantly powerful / radiated transmissions, it'd be possible to get an amateur radio license and then you'd have lots more frequencies available.

Otherwise you could see about receiving a broadcast from a CB or GMRS/FRS radio... I'd think the FRS option might be a bit easier since I think it may be full FM vs. maybe SSB on CB (IDK).

If making a simple semi-passive t/r pair, you might find it easier to eschew using transistorized circuits for the RF aspect of things and consider doing something more passive like modulating existing noise or doing something like a spark gap transmitter that excites a resonant cavity / tuned circuit.

Some of the very early radio work was actually using UHF/microwave frequencies in such manners because one doesn't need circuit elements like fixed and variable capacitors, inductors, one can instead use the natural (and much higher quality -- literally -- Q-factor -- resonance of things like copper sheet metal pipes / boxes / cylinders / spheres, and lengths of plain potentially uninsulated wire as transmission lines, antennas, resonant circuits, tuned circuits, et. al. Much simpler than using discrete lumped element circuit components, and less lossy too usually.

For a FM modulator one could even conceive of using something like Edison's gramophone to vibrate a foil sheet or stylus that changes the resonant frequency of an existing tuned cavity or tuned circuit in response to voice. Of course you could use a battery and electromagnetic amplifier / actuator as a telegraph or early telephone would have done since those were known to various levels since before the 1800's.

If you really want to homebrew active devices, though, I'd agree with others that vac. tubes are the better choices than transistors for simplicity and utility.

On the other hand, there's plenty that can be done with just transformers, electromagnets, relays, dynamic microphones, R, L, C circuits, et. al.

 

[bobsmith1492]

QO - I think you'd be picking up the AM signals rather than FM ones. As a young lad I found hooking an earphone up to a diode let me hear the local AM station broadcasting from a couple of miles away.

 

[Rubycon]

If you're close enough to the transmitter you don't even need a diode! Text

 

[davesaudio]

Originally posted by: Rubycon
If you're close enough to the transmitter you don't even need a diode!

He's about a 120 YEARS away from a transmitter

 

[Nathelion]

The first computers were made with electromechanical relays... a modest generator shouldn't be too hard to make, just a coil of copper wire, a magnet, and a steam engine/water wheel. Not cheap, but feasible. After that, you just make a couple of thousand relays, and voila! You have a pocket calculator. Might affect the future, though it wouldn't help you with the FM radio

 

[Eskimo]

Make it a point transistor like Brattain and Bardeen did. Assuming you can make gold foil, razorblade, and obtain germanium. Video simulation at PBS

 

[BrownTown]

Originally posted by: Nathelion
The first computers were made with electromechanical relays... a modest generator shouldn't be too hard to make, just a coil of copper wire, a magnet, and a steam engine/water wheel. Not cheap, but feasible. After that, you just make a couple of thousand relays, and voila! You have a pocket calculator. Might affect the future, though it wouldn't help you with the FM radio

The only problem here is the ability of the relays to function at the required speed. I mean how fast of a relay do you really think the OP is going to be able to obtain in this time period mentioned? In order to demodulate sound it would have to be pretty darn fast (relatively speaking), so you can't just go running your computer at 10Hz or something because you need it to demodulate sound in real time which is 44100Hz by modern standards.

 

[BladeVenom]

Originally posted by: Born2bwire
You can make vacuum tubes by hand. I would go that route.

It also makes for a really good video.

 

[BladeVenom]

Originally posted by: Modelworks
I was thinking about time travel and what if you went back to say 1800, what kind of technology could I give them then that would effect the future the most.

I would invent antibiotics. Penicillin made a huge impact.

 

[MagnusTheBrewer]

Originally posted by: BladeVenom

Originally posted by: Modelworks
I was thinking about time travel and what if you went back to say 1800, what kind of technology could I give them then that would effect the future the most.

I would invent antibiotics. Penicillin made a huge impact.

Refrigeration would have a bigger impact. It didn't come along till 1805.