Evan K7FOS

I finished some updates to my RF mixer circuit (Gilbert Cell topology), and have been testing it out! 7.1dB drop between the fundamental and mixed frequency, and a max signal-to-noise of 58dB! Not amazing, but it will work fine for my plans.

@freddyphysh @fibersphere I wish they'd at least say what is going on, and perhaps an ETA.

@fibersphere how are we doing with this outage. I’m trying to do some work here

My first successful attempt at solar photography! And all from the convenience of my window!

Lots of breadboarding lately! Fun audio projects to boost my op-amp skills.

Somehow one of my dorkier purchases over the last year -- a 4-foot-wide Pickett slide rule! It was originally used as a teaching aid during the era of slide rules. I am unreasonably happy with finding this one!

AGC circuit I've been working on. (1) Voltage divider w/ an n-channel MOSFET as a variable resistor (2) Buffer amplifier (output green) (3) Peak Detector (output red) (4) Comparator of peak voltage vs reference voltage. Provides feedback to the MOSFET. everycircuit.com/circuit/649813…

Here's what the circuitry looks like, roughly. I built this up when I was learning about double-balanced mixers. everycircuit.com/circuit/562127…

I finished some updates to my RF mixer circuit (Gilbert Cell topology), and have been testing it out! 7.1dB drop between the fundamental and mixed frequency, and a max signal-to-noise of 58dB! Not amazing, but it will work fine for my plans.

New crystal oscillator circuit board! I designed this one to be able to be configured for either series or parallel resonance.

I recently started learning to make active audio filters from opamps. This is the first one I've finished designing! It's a stereo low-pass filter (bass boost), with a 16kHz cutoff. Sallen-key topology, dual-channel, 3x cascaded. #maker #pcbdesign #audiogear

@JLCPCB There is a bug on your "payMethod" page that is preventing me from being able to check-out. Is this a known issue?

I accidentally assigned 0804 resistors for a 0603 footprint, resulting in them looking like crooked teeth. Whoops! I wish the assemblers had rejected the design, but surprisingly it still works! Nonetheless, these PCBs have become the "test batch."

@jhsu Dude. I need to know more. This is really cool. What does it do so far?

Discord bot to raspberry pi running an electron app

Progress!

Two new PCB designs! Colpitts oscillator and a 40dB RF preamp. The overall plan is to eventually build a radio transceiver block-by-block.

@Cluster_M @JLCPCB Oof, I spent way too long regenerating my gerbers, assuming it was something wrong on my end. Glad to know I just need to wait while they get it fixed up.

@jlcpcb Gerber analyzer is not working now?

Initial magloop antenna assembly is complete! After testing it I think it could use a good coat of paint. I need to make a larger coupling loop for it, but this'll do for now.

My quarantine project is coming along nicely! This is the controller for a magnetic loop antenna. It has a vacuum-variable capacitor that's controlled by a Raspberry Pi and stepper motor! I'm hoping to do the final assembly this weekend. 😁

Got the LCD library U8G2 to work with my design! Unfortunately, it isn't connected to the correct SPI pins, so I had to use the software implementation. This is making the screen refresh dreadfully slow... Oh well, one step at a time.

New project! It will be a battery-disconnect module that will auto-disconnect after a specified interval based on either a battery voltage-drop (as what happens when the engine shuts off) or errant power consumption, etc. Now to write the firmware...