[Ronja] A few questions

Karel Kulhavy clock at twibright.com
Tue Oct 30 19:53:41 GMT 2007

On Tue, Oct 30, 2007 at 05:02:12PM +0000, Alec Wright wrote:
> Hi, I'm thinking of making a RONJA but I have a few questions:
> 1. Do I need any PCBs at all, or can i just airwire everything?

You should have a PCB for Twister or Twister2. Transmitter and RX aren't
so critical.

> 2. I can't find anyone who sells 74HC133s required for the twister2.
> Would it be OK to do this instead?
> http://img80.imageshack.us/img80/5181/mmhs9.jpg

If it's wired logically correctly (I didn't check) then yes - what's happening
there with the 133's and the following 32 and 00 is that 17 wires are AND-ed
together. You can use a different method to achieve the same logical result.
Just if some wires encounter longer propagation path in your replacement
circuit, hook them to the 4040 outputs that are lower on the schematic. Since
if the number in these counters increments, the bits flip consecutively from
top to bottom and the whole logic is designed with this assumption. If
this is not met, it could produce glitches - or at least require some
thinking to prove that it won't glitch.

> 3. Could I increase the range by adding more ultra bright LEDs and using
> different lenses? I'm hoping for about a 4km range (!!)

No - only one LED can be in the focus of a lens.

> 4. How high am I likely to have to put a RONJA to go over about 4km of
> city, with no skyscrapers (max of about 3 storey buildings)? Or is RONJA
> designed to go over things like fields, lakes, rivers etc?

I guess it may work, but only in night and when there is no fog. It doesn't
matter over what it goes unless it's just above a hot tin roof or through a
large amount of smoke (one white chimney plume doesn't seem to cause trouble).

>From rough estimations I did by covering part of the Ronja lens, it seems that
the range during clear night is 3 times more than the nominal range.

> Thanks,
> Alec Wright
> -- 
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