Guest
Please read the description first for more relevant info. This is only a VLOG, I will publish the adapted circuit as soon as possible (14 Aug. 2023). Update 16 aug. 2023: still working on the circuit (....). The re-study and re-test of this circuit takes a lot of time, I will only publish it on YT when it is completely OK & reproducable for everyone interested. Correction: on in the video I say that I used a BF245 FET, but that is not true (!). I used here by purpose a BF 256A FET, because the BF 245 (type a,b,c) is obsolete and (as far as I know) no longer made. And when they are made (say in China): my idea (only an idea, correct me if I am wrong...) their quality cannot match to the original Philips made BF 245 (a,b,c) of the 1970's-1980's. Both types are, by the way N-FETS. About a sine wave radio oscillator that works between 381 KC and MC, with only one Field Effect transistor, the BF 256A (N-FET). Though the first schematic (18 February 2023) is already here (without the new adaptations it is visible on in that video): The (“new”) circuit now (12 Augustus 2023) is an elaboration/adaptation of that earlier a circuit, published on 18 February 2023. The circuit of 18 February 2023 did not want to go properly (=undistorted waveforms) to the highest frequency bands (6-8MC). So I stepped back in the frequency range. Now it works from 381 MC instead of the original idea (that was max. 8 MC). It all has to do with working on an electronic setup/situation that “was already there”, I mean: the Farnell setup with that (beautiful) 10-500 pF (or even higher, max 1000 pF) tuning capacitor, beautifully immersed in a metal box, properly shielded on all sides, etc. So as a hobbyist I had to take that for granted and had to take profit of that. By the way: when you want to make radio sine wave oscillators between 300 KC and 15 MC (= higher frequencies) : there are many circuits of them on my YT Channel. Go to my channel trailer (Radiofun232 on You Tube) , go to the “looking glass” and search with words like “oscillator” or “generator” or “shortwave” or “short wave” or “radio” or “radio oscillator” etc. Some are made with BJT transistors, some with FET's. The apparatus that I show here was showed earlier in the video of 8 February 2023, but I left it for a very long time skipped, because it did not want to work the way I wanted. The circuit where this was all about (8 February 2023, about “downgrading” this FARNELL radio oscillator) is in this video: The schematic is on in that video. Other link to the same circuit is here For everyone liking to copy the circuit and do experiments, these are the following adaptations now (12 august 2023) to the circuit of 8 February 2023: 1. The switch (S2) “high-low” is removed 3. The 18 uH (Micro Henry coil) is switched in permanent, thus switch S1 is removed too 4. A resistor of 1 K, directly out of the source (where the 820 uH coil is to ground, say the “ape hair“ coil) goes to the top of a 50 K (47 K) potentiometer. 5. The wiper of that 50 K potentiometer goes to the output electrode/output socket via a non polar capacitor of 10 N (=0,01 uF). To manage the output level of the oscillator. Ground electrode/pin of the of course goes to ground (-). When you don't want to wind that “ape hair“ coil yourself you can use a 820 uH (Micro Henry) factory made coil. The self-wound coil works best (that is my opinion, by the way). More info to come (exact info about how it was made) in the future. The whole circuit with that 1 FET works very good and is enough low impedant (say 50 K-10K). My You Tube channel trailer is here: When you search, search always “NEWEST FIRST” to get the right overview. You can also search via the “looking glass” on my Channel trailer via keywords like ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in. My books about electronics & analog radio technology are available via the website of “LULU”, search for author “Ko Tilman” there. Tilman I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 12 August 2023. UPDATE 14 August 2023. Important: I say that I took the signal out of the Drain. But that is, afterwards (update 14 August 2023), not true..... I took it (as always) out of the SOURCE. Complete schematic will follow ASAP.
