[GreenKeys] Powering a Model 15 currentl loop from a 5VDC 250mA power supply - theory

[Brooke Clarke]

Hi John:

It's not necessary except for very fine pitch parts.
Standard DIP pitch is 0.1" and half pitch is 0.050", both are easy with 
a soldering iron with a small point.
It's the quarter pitch (and smaller) parts that cause problems.
See:
http://www.prc68.com/I/SMT.shtml
I use ExpressPCB and for surface mount get the solder mask.  That makes 
it even easier.  To get solder mask you need to use the ProtoPro service 
where the boards are <= 21 sq in and the longest dimension is 12" or for 
many many the production service where max board size is 12x14".  So far 
the lowest cost way I've found to seperate smaller boards from what you 
get delivered is a pair of tin snips, see: 
http://www.prc68.com/I/8MSB.shtml#TS
the 8" mini shear break did not work out.

Have Fun,

Brooke Clarke
http://www.prc68.com



John Nagle wrote:
> W2HX wrote:
>   
>> How many devices in series do you think your model could handle?
>> Just curious
>>
>> 73 Eugene W2HX
>>     
>
>     One.  It has to be matched to the load.  It's possible to
> build ones for other loads, of course.  You'd need to increase
> C2 and change out the LT3484-1 for a LT-3484-0, which has
> a higher current limit.   You'd have to adjust R4 for a higher
> holding voltage (probably double it), and increase V1 to maybe 7V or so.
> If you want automatic load matching, that costs extra.
>
>     My goal was to run a Teletype from a USB laptop without much
> extra gear.  Multiple machines would go on multiple USB ports.
>
>     Does anybody on here build surface mount, with the little
> computer-controlled toaster oven?
>
> 				John Nagle
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