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Parts - SMTS and such
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Parts - SMTS and such

by Seanernet on Sun Dec 02, 2007 6:47 pm

Can anyone tell me what surface mount parts would be compatible with the attiny85? I've found this one ATTINY85-20SI which is 20MHZ, will it still work at 20MHZ or must it be 10MHZ? Does anyone know the limitations of using surface mounts to create a TV-B-Gone? My main purpose for using surface mounts is to create the smallest possible unit for various concealments.

Thanks in advance,
Sean
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by adafruit on Sun Dec 02, 2007 7:33 pm

the 10mhz chip will run at lower voltages, so it will run longer. other than that, either is ok

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by montag on Sun Dec 02, 2007 8:51 pm

I am doing the same thing. Biggest problem i see is the battery. This circuit uses a fair amount of power when leds are on.

Leavs out coin cells etc.. Working on a Li ion battery from a cell phone making the charging circuit.

Would be about 2"X1.5"X.5"

There are some small keychain enclosures but the battery is still the deciding factor.
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by Seanernet on Mon Dec 03, 2007 2:35 am

Thank you for the responses, that is great. Currently I'm running a key fob version with one led and I'm using 3 button cells harnessed from an A23 battery. So far so good. The led runs very bright and seems to have good range, I'm still in the testing phase. I'm hoping that once I build an SMT version, I'll have more space for other battery options. At first I was concerned running 4.5V to the circuit when Mitch has suggested in the past 1.5V per led. Problem is, the circuit doesn't seem to run at all with less than 2V, which eliminated me using one AAAA battery and I just don't have the space in the enclosure to run a pair. Once we get a full surface mount TV-B-Gone built, one of us should post a full parts list for others to use.

Thx,
Sean
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by maltman23 on Wed Dec 05, 2007 3:16 am

Yeah, you might have some trouble using the 20MHz parts without the "V". The "V" is for low voltage, meaning that the ATtiny85V will continue to work fine down to 1.8v. The non-"V" parts only work down to 2.7v. And while the IR emitters are emitting, the voltage can dip down pretty far, and if the voltage dips down far enough, the chip's Brown Out Detector (BOD) will reset the chip before you've had a chance to transmit all of the POWER codes.

Please do post your results to the forum. I'm curious how things will work for you, and I'm sure others will like to see how things go, too.

Mitch.

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Please be positive and constructive with your questions and comments.