"Bobik" A Tunnel Diode 80m CW Transmitter by AA1TJ
Bobik is an 80m CW transmitter built from a pair of (circa-1976) Soviet-made tunnel diodes. The circuit is a push-pull LC oscillator; frequency-locked to a quartz-crystal.
http://web.archive.org/web/20101124023645/http://aa1tj.com/Bobik.html

"Easy Ten" - A simple 80 Meter CW Transmitter Using A 2N3904 by K7NS
I call this very simple transmitter the "Easy Ten" because it can be easily heard at a distance of 10 miles. Transmitter antenna is a random length wire run through a hole in the wall and thrown into a tree.
http://www.sparkbangbuzz.com/easy-ten/easy-ten.htm

25 part transmitter for the QRP Minimal Art Session by LA3ZA
My Minimal-Art-Session rig shown here was made for class B of the QRP-MAS competition which is in May every year. In class B the transmitter should have a maximum of 50 components, and the fewer the number of components, the more points one will get per contact. With such simple rigs, only CW is viable.
https://la3za.blogspot.com/2005/12/25-part-transmitter-for-qrp-minimal-art.html

3-Watt, 2-Band CW Transmitter by KC6WDK
More ambitious, versatile, and powerful than the 500mW Transmitter is this enjoyable version of a unit that originally appeared June 1967 in QST. A two-stage crystal-controlled rig for 80- and 40-meter CW operation.
https://www.qsl.net/kc6wdk/QRP/transmitter2.htm

3.5MHz ARDF Transmitter by ON7YD
This transmitter is designed as a classic 3 stage TX.
http://www.qsl.net/on7yd/atx80.htm
 

3.5MHz Low Power ARDF Transmitter by ON7YD
This low power transmitter is developed for ARDF exercising purposes but of course can be used as super QRP transmitter either.
http://www.qsl.net/on7yd/minitx80.htm

80 Meter Tube Transmitter by SM5GNN
This is a variation of the triode/pentode family of glowbug transmitters. It features a Pierce oscillator which runs continously during transmit to avoid chirp.
http://www.tuberadio.com/80.html

80 Metre DSB Transmitter by VK3YE
This circuit is probably the simplest practical 'bare-bones' voice transmitter for the 3.5 MHz amateur band.
https://vk3ye.com/projects/proj80ds.htm

80m "1950's Retro" QRP Transmitter by AA1TJ
A "milliwatting" enthusiast enjoys the challenge of communicating on the amateur radio bands while using the lowest possible RF power level. However, along with this challenge, I've recently begun to wonder what are the minimal performance limits of the active devices that I use in my QRP transmitters?
http://web.archive.org/web/20101124023608/http://aa1tj.com/80mqrptransmitter;circa1955.html

80m 0.5w Mini Transmitter by G3ZOI
This 80m ARDF transmitter was designed to be multi purpose, suitable for Classic, Sprint and FoxOring formats. Compact and lightweight and easy to deploy. Low component count. Multipurpose socket for charging/syncro/tune-up. Internal ATU for matching to a short wire antenna.
http://open-circuit.co.uk/wp/transmitters/mtx80/

80m 3W Transmitter ATX-80 by G3ZOI
The 80m TX described here is the well known ON7YD ATX-80 and timer, combined in a standard aluminium enclosure.
http://open-circuit.co.uk/wp/transmitters/atx-80-2/

80-meter CW Transmitter by K9PPW
This is a schematic of Bob's homebrew QRP transmitter. It's CW on 80 meters, about 1 watt output, VFO ... and only uses TWO rf transistors and one more for keying. It was built as an experiment to see what you could get out of ONE transistor (about 250 mw with no chirp) and the "shoes" were added later to get a whopping one watt of rf out.
http://my.core.com/~jematz/qrp/k9ppw-s1.htm

80m Mini Fuchsjagd Sender by DH1DA
Ein kleiner Sender bringt viel Spass in der Natur.
https://dh1da.darc.de/projekte/Amateurfunk/Fuchsjagdsender/DH1DA_80m_FOX-02.pdf

A Simple Modular DSB TX by GMØRWU
The simplest way of getting on the air with phone is to convert a single transistor crystal controlled TX into an AM transmitter by putting a carbon mike in series with the poer supply. A more elegant approach is to use DSB.
http://www.homepages.ed.ac.uk/jwp/radio/projects/dsb/

Built an 80m DSB transmitter - VK3XU's "simplex sidebander" by VK2TPM
Spurred on by the success and what I've learned from my battle with the Bitx20 I sat down and constructed a transmitter from scratch.
It's the "simplex sidebander" from Drew Diamond's "Radio projects for the amateur" first book.
http://blog.marxy.org/2009/01/built-80m-dsb-transmitter-vk3xu.html

Das Derelicht An 80m CW Transmitter by AA1TJ
This electronic puzzle was a result of my changing a defective compact fluorescent lamp (CFL) in my kitchen. For some reason, I began to wonder if it would be possible to build a QRP CW transmitter using the electronic components salvaged from this derelict lamp.
http://web.archive.org/web/20101124023947/http://aa1tj.com/dasderelicht.html

El Silba Voice-Powered 75m DSB Transmitter by AA1TJ
This double-sideband (DSB) radiotelephone transmitter is powered entirely by the instantaneous (not stored) energy produced in the operator's voice. The RF output power in my prototype falls within the range of 5 to 15mW.
http://web.archive.org/web/20101124023634/http://aa1tj.com/elsilbo.html

Fox transmitter for 80m by PA3HCM
One of the members at the club pointed me at the so-called “OXO transmitter”. I looked it up at the internet, and immediately liked its simplicity. So I started to build it.
http://www.pa3hcm.nl/?p=294#more-294

Frequency agile 80 metre CW QRP transmitter by VK3YE
https://vk3ye.com/projects/pro80cw.htm

Micro beacon " Froggie" by OH1TV
This radio transmitter is just for fun. It sounds like a frog when it gives short signals on 3699kHz LSB every second or two.
Transmitting power is very small, less than 1mW. Useful tranmission distance is less than 50m.
Power consumption is very low. One LR20 battery (large 1.5V) can last more than a year.
https://oh1tv.fi/Froggie.htm

New England Code Talker by AA1TJ
In order to complete my first QSO with El Silbo I resorted to sending Morse code, by literally speaking "DIT DAHHH DIT," etc., into the loudspeaker (working backwards as an acoustic to electical power generator). This gave me the idea to build a dedicated voice-powered CW transmitter. I call this CW transmitter the New England Code Talker.
http://web.archive.org/web/20101124023547/http://aa1tj.com/newenglandcodetalker.html

TAG 80 Transmitter by G4RAW
Original Circuit in SPRAT Summer 1994 Iss Nr 79
The original version was built on tag strip, hence the name.
http://www.qsl.net/g3pto/g4raw.html

Ten Minute Transmitter by G4RAW
Steve, G4RAW described this simple transmitter for 80 metres in Sprat 82 and describes how the World record for building a rig , actually a Oner, and having a QSO, is under 15 minutes.
http://www.zerobeat.net/g3ycc/tenmin.htm

The AA8V/W8EXI 6CL6 One-Tube Transmitter by AA8V
In December, 1998 I attended the annual Christmas banquet of the Cuyahoga Falls Amateur Radio Club. At that meeting I got a wonderful Christmas present: Jim Trutko, W8EXI, offered to give me much of his old homebuilt ("homebrew") amateur radio equipment.
https://www.frostburg.edu/personal/latta/ee/6cl6xmtr/6cl6xmtr.html

The Madagascar Mighty Mite by 5R8SV
Over the last few years, there have been a spate of postings from homebrewers taking inspiration from the Soldersmoke podcast to whip up various incarnations of the Michigan Mighty Mite, a very simple rock-bound QRPp transmitter.
http://blog.templaro.com/madagascar-mighty-mite/

The Nipper 3.5MHz Transmitter
I think that this circuit was developed by G3ROO but my notes are lacking in this information.
http://www.qsl.net/g3pto/nipper.html

The Vermont Snowflake by AA1TJ
The Snowflake is built around a 7400 TTL NAND integrated circuit. Two gates comprise the VXO and the other two gates are connected in parallel to form the PA. A 3.58MHz ceramic resonator is used in the VXO circuit.
http://web.archive.org/web/20101124023340/http://aa1tj.com/80mqrpp.html

Tunnel Diode Transmitter by AA1TJ
It's now clear to me why nearly all of the 1960's tunnel diode novelty transmitters were designed for phone rather than CW.
http://web.archive.org/web/20101124023235/http://aa1tj.com/tunneldiodetransmitter.html

Your first transmitter by PA3HCM
With just a few components, you can make your own morse code transmitter. The output is only a few miliwatts, but this is enough to receive on any radio in your home.
http://www.pa3hcm.nl/?m=200208