Yes, Honeywell makes some great stuff - right here in the USA.
Very cool.
Yes, that's right - a shunt in the end is the best most durable solution.
Its why in the end twisting wires (if done correctly) is also another great
solution :-)
On Thu, Jan 12, 2017 at 11:05 PM, Allen Farrington <allen.farrington@xxxxxx>
wrote:
Those are great switches!
So...at the day job, as Mike likes to say...
We don't use switches on the flight hardware. Secondary batteries
(rechargeable) and the main power bus are wired out to a skin (of the S/C)
connector. That way when on the ground, you can use GSE to power the system
and keep the charge state of the batts correct.
When its time to fly, we use a shorting plug, e.g. a connector with pins
wired together, to connect the power all up.
Now that I'm using LiPo's to power my rocket electronics, it occurs to me
that this may be a good way to approach this.
Just some thoughts.
Allen
Terseness and mis-spelling courtesy of my iPhone
On Jan 12, 2017, at 10:38 PM, James Dougherty <jafrado@xxxxxxxxx> wrote:
Getting a Schurter from Bob would be higher probability of success since
he keeps new stock, and boxed.
I've seen students who have used these and they actually popped apart
after various test/setup cycles on the range;
it was entertaining.
An MTBF of 300 cycles is actually quite poor, keep in mind these switches
were designed to be turned ONCE when
high power equipment is installed and the technician needs to switch to a
220 or 120V AC power main. Also, keep in mind that
the function of the switch is ON-ON (it selects 120/220) so one cycle is
one flip (either way). We use it for an On/off switch (ON-OFF) which means
you would cut that MTBF in half (we flip that switch back and forth). Now
it is rated at 150 cycles.
Given I will power on/off my electronics a dozen or so times before every
flight,and that says nothing of the origin of
the switch since somebody may have "tested" it a dozen times before I got
it.
So I think this is what is happening. Those switches have a lifetime, that
is all - people just need to be aware of it
and keep track of that. With those numbers it's easy to get some faulty
units.
The best switch to get is the Honeywell 1TL1-D (https://sensing.honeywell.
com/switches/standard-toggle-switches/TL-series)
MS24523-22 - it is a military grade switch that will operate underwater
and you will find 100's of these in any Boeing cockpit.
MIL-DTL-3950H specifies 40,000 cycles which is the full operation of the
switch (on/off on-off-on, etc) under a range of temperature and
environmental conditions - so that is the extreme high end.
On Thu, Jan 12, 2017 at 9:12 AM, Kurt Gugisberg <kurtgug@xxxxxxxxx> wrote:
I have used those rotary switches for years. I haven't had one split
apart on me and I'm not sure if I have had any failures either, although I
had one in the ill fated Nibbles flight last year with it's total
electronic failure. So it could have failed. I also use screw switches
alot, the Featherweight switch as well as the Aerocon screw switch. They
are, more or less, foolproof.
Also, three hundred operating cycles would be a lot in rocketry.
Kurt
On Thu, Jan 12, 2017 at 8:13 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Hum, that doesn’t sound good. I’ll have to take a look at what Mike has
designed. It would be nice if a retrofit would fit inside the existing
hole used for the 110/220 switch. Or, perhaps remove the guts from the
110/220 and replace it with something more durable/reliable.
*From: *James Dougherty <jafrado@xxxxxxxxx>
*Sent: *Thursday, January 12, 2017 8:09 AM
*To: *roc-chat@xxxxxxxxxxxxx
*Cc: *Mike Kramer <kramer@xxxxxxxxxxxx>
*Subject: *[roc-chat] Re: Switch Warning with StratoLogger CF
They split in half!!
Ive also seen people turn them and they split in half.
Its designed for a wall socket!
Yes, do what Mike said - great plan; Never seen that fail ...
Sent from my iPhone
On Jan 12, 2017, at 7:22 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Yes, I would like to try this out Mike, please send the file. I’ll look
into the materials available for the printer. I think I only have PLA at
the moment. How about ABS?
*From: *Mike Kramer <kramer@xxxxxxxxxxxx>
*Sent: *Thursday, January 12, 2017 7:09 AM
*To: *ROC Chat <roc-chat@xxxxxxxxxxxxx>
*Cc: *ROC Chat <roc-chat@xxxxxxxxxxxxx>; James Dougherty
<jafrado@xxxxxxxxx>
*Subject: *[roc-chat] Re: Switch Warning with StratoLogger CF
richard,
I use micro switches with a screw to arm them. Uses a small hole in the
side of the rocket and makes it highly unlikely that the electronics can be
in advertently armed.
Easy to 3d print the mount for it. I will send you a file tonight.
Side note, don't use PLA ( unless it is the pro spec kind) for parts, it
can't survive the temperatures on the lake bed. I'm using PETG or Nylon.
Mike K
On Jan 12, 2017, at 6:47 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
I just purchased a PerfectFlite StratoLoggerCF altimeter and the
documentation came with a *Switch Warning* about failures of the
110/220 rotary switch that some people have been using for powering
electronics. High resistance and intermittent connection are noted in the
document.
The document says “numerous reports” of failures, but I’m curious if
this is a problem with a group/lot of these switches or a pervasive problem
to this particular switch or rotary-type switches in general when used for
rocketry. I’ve used these switches in the past and tested the 4 I’m
currently using on two projects. I’m not detecting any problems with these
switches.
Please keep in mind that there are several variations for this make of
switches. Here’s some info on what I have:
Schurter, Voltage Selector Switch, 2 Stages, Series-Parallel, SWA1 or
SWA2
Also, it’s interesting that the spec sheet says that the lifetime is
300 operating cycles (without load).
*So, does anyone have a personal experience that was bad with these
switches?*
Also, I think many people would be interested in recommendations on
arming switches both commercial and custom.
Thank you,
Richard Dierking
