[HN Gopher] Can a Biologist Fix a Radio?
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Can a Biologist Fix a Radio?
Author : tambourine_man
Score : 28 points
Date : 2022-07-10 14:41 UTC (8 hours ago)
(HTM) web link (www.cell.com)
(TXT) w3m dump (www.cell.com)
| kens wrote:
| The radio schematic in the paper looks kind of unusual, with a
| dual-gate MOSFET. Also a bunch of varactor diodes for tuning. Any
| radio experts want to comment on this circuit? I think it's FM,
| but I'm not sure.
| iasay wrote:
| 330uH is a pretty big inductor for FM/VHF. RV1 controls RF gain
| (think of TR1 as two JFETs, one a current source and one a
| common source amplifier in a small signal model). TUNE VOLTS
| changes the resonant frequency of the two tank circuits.
| TR2/TR3 is an impedance buffer. The rest is decoupling.
|
| Looks like a tunable preselector to me rather than a receiver.
| So part of a receiver yes.
| formerly_proven wrote:
| I don't think that's a radio, just an antenna amplifier. I'm
| not seeing where demodulation would happen. Some values seem
| kinda weird to me, like R4 on top of the cascode seems sorta
| high for something that oughta have a lot of bandwidth (and the
| way L2+C6 are drawn is odd). Likewise 390k on the emitter of
| Tr3, seems like very little room for bias for something that's
| supposed to drive 50 ohms. Bandwidth at the input looks to be
| <2 MHz, so maybe it's meant for AM broadcast or 160m.
| iasay wrote:
| R4 controls the output impedance of TR1. It'd have to be high
| to keep the loaded Q of the L2 tank high. R10 looks like a
| mistake to me. Probably should be 390 ohms.
|
| Agree with your assertions though.
|
| It might have been reverse engineered from something badly or
| drawn up by someone smoking crack. Even Tektronix had that
| problem on occasions in their service manuals ...
| joshuahedlund wrote:
| My impression from reading _The Computer Scientist's Guide to
| Cell Biology_ is that the reason for woefully inadequate
| descriptions of cellular systems, rather than any fundamental
| deficiency on the part of biologists, is that the systems are so
| dang tiny and crowded, with every molecule running into every
| other molecule every second or so, at sizes literally below the
| widths of light waves, that we just don't have the tools to
| physically observe what's happening in real-time. Even the
| primitive equivalents of "shooting individual components" took so
| much clever innovation and hard work to figure out how to do that
| frankly it's amazing that we know everything that we do.
| nextos wrote:
| There are interesting attempts at modeling cells using Boolean
| networks (for example inferred using SAT/SMT), differential
| equations (preferably stochastic) and also with process
| algebra. Some are pretty successful.
|
| > [...] we don't have the tools to physically observe what's
| happening in real-time
|
| We do have single-cell technology, which is pretty close as you
| can get thousands of snapshots of different cells from the same
| lineage. One can then reorder them into some sort of
| pseudotime. There are also interesting real-time reporting
| systems for bacterial cells, but they are not high throughput.
|
| I think the field is still very young, and the current
| generation of biology professors is mostly allergic to
| formalism. Some departments are not, a notable exception are
| Caltech and Cold Spring Harbor (where the author of the essay
| is based).
|
| A related read is Luca Cardelli's followup: Can a systems
| biologist fix a Tamagotchi?
| http://lucacardelli.name/Papers/Can%20a%20Systems%20Biologis...
|
| And much deeper: Abstract Machines of Systems Biology
| http://lucacardelli.name/Papers/Abstract%20Machines%20of%20S...
| SilasX wrote:
| >is that the systems are so dang tiny and crowded, with every
| molecule running into every other molecule every second or so,
|
| Per my two earlier comments [1], I would phrase it as an issue
| of biological systems optimizing soley for fitness, while
| (human-designed) computers are also heavily optimized for
| intelligibility, modularity, and ease of reasoning about. This
| makes it much easier to isolate and experiment with the
| subsystems and gain an understand, in contrast to biological
| systems, which will constantly bleed state across the entire
| system.
|
| [1] https://news.ycombinator.com/item?id=31710268
|
| https://news.ycombinator.com/item?id=16818220
| Terr_ wrote:
| The author kinda touches on that with:
|
| > Another argument is that we know too little to analyze cells
| in the way engineers analyze their systems. But, the question
| is whether we would be able to understand what we need to learn
| if we do not use a formal description. The biochemists would
| measure rates and concentrations to understand how biochemical
| processes work. A discrepancy between the measured and
| calculated values would indicate a missing link and lead to the
| discovery of a new enzyme, and a better understanding of the
| subject of investigation.
|
| > Do we know what to measure to understand a signal
| transduction pathway? Are we even convinced that we need to
| measure something? As Sydney Brenner noted, it seems that
| biochemistry disappeared in the same year as communism
| (Brenner, 1995 ). I think that a formal description would make
| the need to measure a system's parameters obvious and would
| help to understand what these parameters are.
| jwilk wrote:
| (2002)
|
| Previous discussions:
|
| June 2022: https://news.ycombinator.com/item?id=31697757 (22
| comments)
|
| January 2022: https://news.ycombinator.com/item?id=30120457 (19
| comments)
| dang wrote:
| Thanks! Macroexpanded:
|
| Related:
|
| _Can a biologist fix a radio? Or, what I learned while
| studying apoptosis (2002)_ -
| https://news.ycombinator.com/item?id=31697757 - June 2022 (21
| comments)
|
| _Can a biologist fix a radio?-Or, what I learned while
| studying apoptosis (2002) [pdf]_ -
| https://news.ycombinator.com/item?id=30120457 - Jan 2022 (18
| comments)
|
| _Can a Biologist Fix a Radio?_ -
| https://news.ycombinator.com/item?id=624695 - May 2009 (4
| comments)
|
| Note the small thread from 2009 there. I could swear there have
| been others though?
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