Hackers' Pub

Syntax	Description	Examples
`"` keyword `"`	Finds the string within quotes, including spaces. Case-insensitive. (Escape quotes inside with `\"`)	`"Hackers' Pub"`
`from:` handle	Finds content written by the specified user.	`from:hongminhee` `from:hongminhee@hollo.social`
`lang:` ISO 639-1	Finds content written in the specified language.	`lang:en`
`#` tag	Finds content with the specified tag. Case-insensitive.	`#HackersPub`
condition condition	Finds content that satisfies both conditions on either side of the space (logical AND).	`"Hackers' Pub" lang:en`
condition `OR` condition	Finds content that satisfies at least one of the conditions on either side of the OR operator (logical OR).	`#HackersPub OR "Hackers' Pub" lang:en`
`(` condition `)`	Combines the operators within the parentheses first.	`(#HackersPub OR "Hackers' Pub" OR "Hackers Pub") lang:en`

Ken Shirriff @kenshirriff@oldbytes.space

8/2/2025, 3:48:10 PM

Public

The most unusual components in the chip are the "varicap diodes", which help adjust the radio's frequency. These special diodes act as capacitors with a value that can be controlled by changing the voltage.

A die photo showing the diodes. They look like interlocking comb teeth between two square bond pads. A diagram below shows how the diodes look on the schematic. This is a normal diode symbol (arrow and line), with a small capacitor symbol above.

Ken Shirriff @kenshirriff@oldbytes.space

8/2/2025, 3:48:17 PM

Public

The chip uses these components to turn an FM radio signal into audio by combining an oscillator, mixers, filters, amplifiers, and other circuits. If you want to know more about this FM radio chip, I go into great detail in my blog post: https://www.righto.com/2025/08/reverse-engineering-analog-TDA7000.html

How to reverse engineer an analog chip: the TDA7000 FM radio receiver

Have you ever wanted to reverse engineer an analog chip from a die photo? Wanted to understand what's inside the "black box" of an integrate...

www.righto.com

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