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What was your first circuit? Do you still remember it?
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schmitt trigger:
My first fully electronics project that I actually built from scratch was a directly-mains powered, 5-tube amplifier. The vast majority of the components were salvaged from old radios.

I already understood the essential operational principles, having fully read Basic Electronics, by Van Valkenburgh, Nooger & Neville, but the negative feedback thing was a big mistery to me...so I just put a resistor and a capacitor network, which I copied from an old radio.

Days later, as I was listening to a vinyl record, my sister came to me: "I can listen to your music on my radio"
In disbelief, I went to her room and, indeed, my music was being broadcast on a spot within the AM band (560 - 1600 Khz).

It took me several years, while studying my EE degree, to realize that my kludgy negative feedback was actually positive feedback and the amplifier was oscillating like crazy, and the music would effectively modulate the oscillation and I had, in fact, built an AM transmitter!
bjcuizon:

--- Quote from: schmitt trigger on July 28, 2017, 08:51:20 pm ---My first fully electronics project that I actually built from scratch was a directly-mains powered, 5-tube amplifier. The vast majority of the components were salvaged from old radios.

I already understood the essential operational principles, having fully read Basic Electronics, by Van Valkenburgh, Nooger & Neville, but the negative feedback thing was a big mistery to me...so I just put a resistor and a capacitor network, which I copied from an old radio.

Days later, as I was listening to a vinyl record, my sister came to me: "I can listen to your music on my radio"
In disbelief, I went to her room and, indeed, my music was being broadcast on a spot within the AM band (560 - 1600 Khz).

It took me several years, while studying my EE degree, to realize that my kludgy negative feedback was actually positive feedback and the amplifier was oscillating like crazy, and the music would effectively modulate the oscillation and I had, in fact, built an AM transmitter!

--- End quote ---

Nice! :-+ ..haha, Building an AM Radio transmitter from scratch without even knowing it. :-+ Great stuff!
ManuelMcLure:
I don't remember what the exact circuit was, but it was made using a Denshi Block kit back in the 70s. We had several of these but the best was the SR-4A Deluxe: http://searle.hostei.com/grant/ElectronicKits/index.html#DenshiBlockSR4A
bd139:

--- Quote from: schmitt trigger on July 28, 2017, 08:51:20 pm ---I already understood the essential operational principles, having fully read Basic Electronics, by Van Valkenburgh, Nooger & Neville,
--- End quote ---

I love the artwork in those books. I wish people made that much effort now.
Zero999:

--- Quote from: bjcuizon on July 25, 2017, 07:01:33 am ---Hi, I found out that there were already threads about something like your first multimeter, etc. Now, I think sharing (and maybe talking) about our first circuit would be fun as all of us had our beginning days.  :) ...And hopefully, it could inspire and motivate some beginners and newbies too.

So here we go, let's start with mine.
Back in the day, when I was 8, I was really interested in analog audio stuff. I was not really interested in electronics back then, I just loved connecting wires (and lots of them) on audio systems ::). But while surfing on the web, I was directed to this circuit which says that the LEDs will light up depending on the intensity of the sound.

I then went to my local electronics shop to buy some parts and connected some bare wires to the transistor. And to my excitement, it worked perfectly!
This was a thing of beauty for me and so that's how I got into electronics.

Anyway, that was my beginning. What's yours?

--- End quote ---
Notice there's no current limiting resistors for the LEDs or transistor's base? You're lucky it worked and didn't blow up! I suppose it needed careful adjustment of the volume control.
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