[ShaneP]

I2C does not have a set length: bus capacitance is the limiter. IIRC, this is around 400pF.

In the past, since I only needed to run one segment of cable, I used Texas Instruments P82B96 on each end.

Page 55 of that application note I linked shows a different arrangement that may be suitable for your application (I'm thinking a centralized controller).

There's a good bit of info out there, and I might want to do something similar soon.

http://focus.ti.com/lit/ds/symlink/p82b715.pdf (P.8 buffered bus)
http://focus.ti.com/lit/ds/symlink/pca9517.pdf (p.10 series repeater)

 

[dean0]

RCA Switchbox I made earlier
-2 Inputs
-4 Outputs

 

[grawk]

I love chickenhead bakelite knobs

 

[dean0]

Quote:

Originally Posted by grawk /img/forum/go_quote.gif I love chickenhead bakelite knobs

thanks!

 

[linuxworks]

not quite a full build, yet, but its somewhat new.

the old arduino is now controlling 2 digital pot chips!

yeah, I know, ugly rat shack knob. I'll replace it some day (lol).

what's going on in the pic is that the arduino is reading the value from the ugly blue knob and scaling it to an 8bit value (0..255) and showing this in dB. that dB value is then sent out to a port expander chip (phililps dip16 in the perf board) via i2c (blue and black twisted wire). from THAT, we get bunches of 3bit SPI data that is sent to both digital pot chips (the pot chips speak SPI even though the chip above it is i2c). its confusing but I do prefer i2c for doing all my 'control' things and yet the i2c native chips are all tsop and/or use ugly ways to talk to them over i2c. the spi based chips, for some reason, come in soic8 and also dip8 and their software interface is much simpler.

what I plan to use this in: basically anywhere a real pot would go, this thing may be able to fit, also. as an input attenuator before an amp; as a gain setter (feedback R in op-amps), as computer-controlled bass boost (in the amps that have dual pot based BB features) and maybe even auto calibration of bias and offsets in trimmer-settable amps.

the 3 leds are there for debugging; the red one is 'power=ok'; green=global chip-select and orange is global clock.

firmware will be uploaded (source) shortly in case anyone wants to try to replicate/experiment with this.

 

[fishski13]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif not quite a full build, yet, but its somewhat new. the old arduino is now controlling 2 digital pot chips! yeah, I know, ugly rat shack knob. I'll replace it some day (lol). what's going on in the pic is that the arduino is reading the value from the ugly blue knob and scaling it to an 8bit value (0..255) and showing this in dB. that dB value is then sent out to a port expander chip (phililps dip16 in the perf board) via i2c (blue and black twisted wire). from THAT, we get bunches of 3bit SPI data that is sent to both digital pot chips (the pot chips speak SPI even though the chip above it is i2c). its confusing but I do prefer i2c for doing all my 'control' things and yet the i2c native chips are all tsop and/or use ugly ways to talk to them over i2c. the spi based chips, for some reason, come in soic8 and also dip8 and their software interface is much simpler. what I plan to use this in: basically anywhere a real pot would go, this thing may be able to fit, also. as an input attenuator before an amp; as a gain setter (feedback R in op-amps), as computer-controlled bass boost (in the amps that have dual pot based BB features) and maybe even auto calibration of bias and offsets in trimmer-settable amps. the 3 leds are there for debugging; the red one is 'power=ok'; green=global chip-select and orange is global clock. firmware will be uploaded (source) shortly in case anyone wants to try to replicate/experiment with this.

i would love to attempt to integrate the LCDuino-1 with my B1 buffer.

 

[FraGGleR]

Quote:

Originally Posted by dean0 /img/forum/go_quote.gif RCA Switchbox I made earlier -2 Inputs -4 Outputs

Very nice! Is that a copper plate for ground and rigidity? I am thinking about a similar setup, just housed within the same case as my dac and amp.

 

[sam_cat]

My 3rd build, a cmoy with voltage divider:

TLE2426CP chip (voltage divider)




TAKMAN metal film Resistors:




Finished article:






More to follow, just building a gainclone/starfish combo at the moment.


Linuxworks, Lovely work with the Arduino intergration.. Just got one myself, learning the basics on it at the moment (nice and easy isnt it!) before worrying about intergrating it..

Thanks,
Sam C

 

[Kerry]

Here is my latest creation. It is a relay with a delay for the HV so the filaments can heat up first. I'm putting in my Blue Hawaii.

It has two indicators, one for the power and one for the HV on. I added some additional functionality so that if the umbilical is not connected it will not turn on the HV and just flash the power indicator. This could also be used for thermal sensors too.

Here are the boards. One is the relay and the other is a new version of the BH PS (you gotta tweak

).

Here's the build progress...

I'm not done yet but I've tested the critical parts and it works.

Always a concern with new boards.

 

[johnwmclean]

Wonderful Kerry.

 

[fishski13]

Kerry,
that's hardcore. please post more pics of your build as you progress.

 

[nattonrice]

Kerry as always... damn O.O
Very awesome!

 

[Kerry]

Thanks guys.

I will definitely post more pics as I progress.

 

[El_Doug]

Wow Kerry, you sure copped out by not etching these yourself! Shame on you

 

[spritzer]

I'm at least somewhat to blame there...