CAPT Bligh
New Member
Hello all, new here and looking for help and advice, of course...
I am thinking of a project for a geocache. This is a hobby where you hide a "cache" (usually a watertight plastic container or an ammo can) in the woods somewhere, post the coordinates online and other people go searching for it using a handheld GPS. The cache usually contains trinkets for trading and a logbook for recording the find. Search on geocaching if you're interested.
My project would be part of a multi-stage cache. Mounted inside this container would be a panel with a row of seven ON-ON toggle switches and some 7-segment LEDs. The finder would have to figure out the correct position for all the switches in order to display the coordinates of the next stage (there would be clues on the cache page to help with this). If the switches were set in any configuration except the correct one, the display would be random gibberish.
The first few coordinates would be given (printed on the panel), with the LEDs supplying the final three digits, like this:
N 38 34.XXX
W 076 12.XXX
with the LEDs sitting where the x's are.
I've poked around Digi-Key and come up with this for the display: https://www.electro-tech-online.com/custompdfs/2010/02/LDS-CA14RI.pdf
So I've got 42 segments to power, and 14 switches (7 two-position switches). So each switch position will light 3 segments, not necessarily on the same module. I'll wire it up to show the correct numbers when the switches are set properly, and randomly connect the other settings.
So on to the questions:
The datasheet for these displays shows a 4V forward and 5V reverse voltage. So I need a 5V power supply, right? Can I just stack three (or four?) 1.5V batteries together, or do I need a more complicated power supply?
Steady current is given as 30 mA. So is this just a current divider problem? 5V/0.03 = 167 ohms, so I should put 167 ohms in series for each segment?
Is there anything else that should be included on this simple circuit--capacitors, shunt resistors, other things I'm too ignorant to know about?
If you understand what I'm trying to do, is there anything that could improve the "coolness" factor of this, without making it too complicated (don't want people frustrated out in the middle of the woods on a multi-stage)?
Thanks in advance for any advice.
CB
I am thinking of a project for a geocache. This is a hobby where you hide a "cache" (usually a watertight plastic container or an ammo can) in the woods somewhere, post the coordinates online and other people go searching for it using a handheld GPS. The cache usually contains trinkets for trading and a logbook for recording the find. Search on geocaching if you're interested.
My project would be part of a multi-stage cache. Mounted inside this container would be a panel with a row of seven ON-ON toggle switches and some 7-segment LEDs. The finder would have to figure out the correct position for all the switches in order to display the coordinates of the next stage (there would be clues on the cache page to help with this). If the switches were set in any configuration except the correct one, the display would be random gibberish.
The first few coordinates would be given (printed on the panel), with the LEDs supplying the final three digits, like this:
N 38 34.XXX
W 076 12.XXX
with the LEDs sitting where the x's are.
I've poked around Digi-Key and come up with this for the display: https://www.electro-tech-online.com/custompdfs/2010/02/LDS-CA14RI.pdf
So I've got 42 segments to power, and 14 switches (7 two-position switches). So each switch position will light 3 segments, not necessarily on the same module. I'll wire it up to show the correct numbers when the switches are set properly, and randomly connect the other settings.
So on to the questions:
The datasheet for these displays shows a 4V forward and 5V reverse voltage. So I need a 5V power supply, right? Can I just stack three (or four?) 1.5V batteries together, or do I need a more complicated power supply?
Steady current is given as 30 mA. So is this just a current divider problem? 5V/0.03 = 167 ohms, so I should put 167 ohms in series for each segment?
Is there anything else that should be included on this simple circuit--capacitors, shunt resistors, other things I'm too ignorant to know about?
If you understand what I'm trying to do, is there anything that could improve the "coolness" factor of this, without making it too complicated (don't want people frustrated out in the middle of the woods on a multi-stage)?
Thanks in advance for any advice.
CB