tv-be-gone modification.

DickCappels

Joined Aug 21, 2008
5,899
Just a note: If this is a one-off, then the 555 approach is fine. If you are going to make many of these, they you probably want to learn something about the ATTINY85 and use the free AVRStudio from Atmel to program in a 5 minute timer routine to initiate sending of the code. No need for an extra chip, but not worth the effort for only one.

Enough abou that...
 

SgtWookie

Joined Jul 17, 2007
22,201
OK.
On the original diagram you posted, at the lower left is shown "BATT", with two connections.
Just to the right of that, you'll see the upper of the two wires is connected to a "VCC" symbol.
The lower of the two wires is connected to a "GND" symbol.
To the right of the "VCC" symbol, you'll see that VCC is also connected to pin 8 of the ATTINY. The VCC on your circuit is the supply voltage.

Now look at the schematic that I posted.
Note that the top of R1, pins 4 and 8 are all connected to Vcc = 5v. That is the supply voltage input to my schematic.

Does that make more sense now?
 

Thread Starter

burningbridges43

Joined Jan 6, 2009
15
So I pretty much constructed everything.

I still wasn't sure about the output on the tvbegone so I'm using alligator clip temporarily. Nothing happens when I clip it on, wait ten minutes...nothing . But it goes off when I remove it.

btw I'm using a 2.2uf capacitor because I couldn't find the one you said. They guy at the store said it would just affect the timing. I hope thats right.


edit: I just attached it to pin1 of the attiny85. and it might be working. :) yay!
 
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SgtWookie

Joined Jul 17, 2007
22,201
So I pretty much constructed everything.

I still wasn't sure about the output on the tvbegone so I'm using alligator clip temporarily. Nothing happens when I clip it on, wait ten minutes...nothing . But it goes off when I remove it.
What goes off? The TV?
btw I'm using a 2.2uf capacitor because I couldn't find the one you said. They guy at the store said it would just affect the timing. I hope thats right.
What kind of capacitor is it? Is it polarized? If so, did you connect it so that the negative terminal was to ground (your battery negative?)
 

Thread Starter

burningbridges43

Joined Jan 6, 2009
15
the device goes off. (the tvbegone has a led that flashes when it is working)

It is a 35v dipped tantalum capacitor. I double checked it when I put it in. hmmm
 

SgtWookie

Joined Jul 17, 2007
22,201
the device goes off. (the tvbegone has a led that flashes when it is working)
OK, so does the TVBeGone ever flash when your circuit is connected?
It is a 35v dipped tantalum capacitor. I double checked it when I put it in. hmmm
Tantalum caps have their + lead marked. Why, I can't tell you - nobody else has a good explanation for it either. :rolleyes: Did you put the + lead away from ground?
 

Thread Starter

burningbridges43

Joined Jan 6, 2009
15
It will flash when i connect it to pin one of the attiny85 (and the tv will go on/off respectively Same thing when I remove it.

the capacitor is in correctly. the +lead is not grounded.

Should I have used a 48 Kilohm resistor for R2?
 

SgtWookie

Joined Jul 17, 2007
22,201
R1: 4.7 Megohms
R2: 47K Ohms
C1: 1uF-2.2uF
For C1, a 1uF cap would give you about 3 minutes, 20 seconds between cycles.
2.2uF should give you about 7 minutes 20 seconds between cycles.
 

SgtWookie

Joined Jul 17, 2007
22,201
I'm wondering what voltage you're reading on the ATTINY side of S1, in comparison to what you're reading across the battery terminals?

If they're not close, you may have to go to a CMOS version of the 555.
 
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