Posts Tagged ‘Books I Like’

WTPA2 4046-based V-to-F Circuit, take 2

Saturday, June 12th, 2010

Boom! Current sinks all the way:

Because I am late to a BBQ I will not bother here to kick on the corporate dog and grumble about how not a single Rat Shack in downtown Brooklyn sells solderless breadboards. I will however sing the praises of H&H (buy that book. I’m not kidding) and the value of the current sink in the previously discussed VCO clock circuit. I soldered this mess up on some perfboard and in short order had a VCO that happily went from DC to >> 1MHz! The linearity is TERRIBLE, but it proves that the range is there. I’m pretty sure I can fix it adequately for my needs with just fiddling with the passive components in this circuit. Hopefully. Here’s the schematic, captured in time honored analog fashion:

Those component values are way stupid, but I think this is the topology. I may yet get away without the op-amp. Live and learn. And happy BBQing.

WTPA v0.95 Assembled, Other Nerd Biz

Thursday, November 6th, 2008

The nerd-biz has been thick since my last post — Chicago-based rocketry’s own Ignignokt ate peroxide in New Mexico, I finished making a bunch of art pieces / circuits for my man Cory (who is putting them in a show this month at Team Gallery which opens on November 13th — those of you in New York should definitely crash it), I made some fancy LED illumination for a furniture firm here in Chicago, and we have a new President who I’m told has a Twitter account. As of now I’m currently playing hooky on an Embedded radio project which is due soon for another buddy of mine.
Sadly this means that I’ve been a big slacker w/r/t WTPA, but I did manage to assemble the HOT NEW circuit:

In this photo if you look closely you can see that the board is up and running, drawing a reasonable amount of current and turning on the power light. It’s back to a pricey and involved Hello World, but I’m excited to get the code up to speed soon. Truth be told I’m about ready to flip out and just finish this project since it’s been all up in my free time for half a year now, and I can’t wait to get on to some NEW electronic instrument design. I just got this great book and it is both inspiring and incredibly useful — it makes me remember why I fell in love with the humble emitter follower all those centuries ago :-)

PS: Here are some random hard-earned nuggets of electronic design arcana I discovered during that artsy Video Game Controller-Controller job:

  • On the AVR, DORD flips the order in which the bits are _received_ as well as transmitted.
  • Surprisingly I’ve seen the AVR (mega164p) run at 20MHz more often than not at 3.4vDC. I only saw one misbehavior that looked like an oscillator burp.
  • The INVALID pin on the Max3221 is useful as hell. The TSSOP-16 package gives me more bridged pins than anything else I’ve ever soldered, however.
  • Serial Terminal Dumps — use “script -a LogFile” then “term” or “kermit” or “screen” or whatever. You can also do this with Minicom and the escape-L command. Or “term” and “tee”. And you will be totally buggered if you try this on a Mac b/c of its bizzare “cooked” serial drivers.
  • A weird thing about doing SPI with the Playstation One: You can send an ACK pulse TOO FAST after serial byte exchanges with some games, and the console will abort the transfer. I had to add nops in my interface. Also — this is only true for some games (EA Sports, are you listening?)
    • Corrollary: Some games (specifically EA sports games) will bail on you and pause if you have a bad controller exchange during play — I think this is an effort on the developers to help the player in case they pull a controller out in the heat of competition, and it makes sense, but MAN was it annoying to me and required a lot of workaround.