Woodstock battery modification
|
09-10-2016, 08:19 AM
Post: #1
|
|||
|
|||
Woodstock battery modification | |||
09-10-2016, 10:34 AM
Post: #2
|
|||
|
|||
RE: Woodstock battery modification
interesting. I wonder what the diodes are for. they might protect the caps from overvoltage?
|
|||
09-10-2016, 10:59 AM
(This post was last modified: 09-10-2016 10:59 AM by Maximilian Hohmann.)
Post: #3
|
|||
|
|||
RE: Woodstock battery modification
(09-10-2016 10:34 AM)damaltor Wrote: they might protect the caps from overvoltage? Rather the calculator! This looks like a fairly primitive circuit for smoothing the current (capacitors) and limiting the voltage to the calculator (diodes, maybe one of them a Zener-diode?). I would not want to use any of my woodstocks like this, rather connect them to a properly regulated and protected power supply set to 2.5V. Or, as I prefer, use it with externally charged batteries and hide the original chargers very deep inside some drawer... |
|||
09-12-2016, 01:01 AM
Post: #4
|
|||
|
|||
RE: Woodstock battery modification
I have just been rebuilding the power circuits in a bunch of HP-21's and this looks like the substitute for batteries circuit from http://www.cs.ubc.ca/~hilpert/eec/calctd/HP21.pdf.
The Si diodes each have ~07.V drop which get you up to the 2.1-2.8V range. |
|||
09-12-2016, 01:19 AM
Post: #5
|
|||
|
|||
RE: Woodstock battery modification
BTW, I just prototyped models for the woodstock battery case at shapeways. They seem a little rough but work.
Bottom: https://www.shapeways.com/product/CT8EMA...bottom-std Top: https://www.shapeways.com/product/ZKFJHGDJM/ |
|||
09-12-2016, 02:26 AM
Post: #6
|
|||
|
|||
RE: Woodstock battery modification
(09-12-2016 01:19 AM)Nate Martin Wrote: Top: This link seems to be bad; at least it was for me. Once released, will you add these into the existing store that has the 41C and 71B parts? --Bob Prosperi |
|||
09-12-2016, 06:04 AM
(This post was last modified: 09-13-2016 08:01 AM by Sadsilence.)
Post: #7
|
|||
|
|||
RE: Woodstock battery modification
(09-10-2016 10:59 AM)Maximilian Hohmann Wrote:(09-10-2016 10:34 AM)damaltor Wrote: they might protect the caps from overvoltage? Agreement. It is a workaround as woodstock's power adapter delivers ac and too much output voltage for directly driving calculator. Some capacitors and diodes can do ac/dc conversion and voltage cut. Nevertheless curcuit looks frightening simple ;-). P.S. Found a similiar curcuit in an HP19C (Only 1 capacitor and 1 diode ;-)) and it is (after remodifcation) still alive... |
|||
09-13-2016, 02:58 AM
(This post was last modified: 09-13-2016 03:01 AM by Adam Vaughn.)
Post: #8
|
|||
|
|||
RE: Woodstock battery modification
IMO, those capacitors should be replaced before you use that calculator much longer. They look rather old, and electrolytic capacitors don't have an indefinite lifespan (often 10-20 years, sometimes 30-40 if you're lucky). Use values as close as possible to the existing caps, to be safe. Might not be a bad idea to replace the diodes, while you're at it. Make sure to match the polarity of the new parts to how the old ones were wired in.
-Adam |
|||
09-13-2016, 04:03 AM
Post: #9
|
|||
|
|||
RE: Woodstock battery modification
(09-12-2016 02:26 AM)rprosperi Wrote:(09-12-2016 01:19 AM)Nate Martin Wrote: Top: I am doing small adjustments to the bottom, once I have them working well I will open up to everyone. |
|||
« Next Oldest | Next Newest »
|
User(s) browsing this thread: