Today's Message Index:
----------------------
1. 08:25 AM - Re: Poor Man's Battery Tester (Dick Tasker)
2. 10:38 AM - LED question (Rod Smith)
3. 11:37 AM - Re: LED question (Kent or Jackie Ashton)
4. 11:46 AM - Re: LED question (user9253)
5. 11:53 AM - Re: LED question (user9253)
6. 08:10 PM - Re: Poor Man's Battery Tester (Robert L. Nuckolls, III)
7. 10:18 PM - Re: Poor Man's Battery Tester (Jeff Luckey)
8. 10:28 PM - Re: Poor Man's Battery Tester (Jeff Luckey)
Message 1
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| Subject: | Re: Poor Man's Battery Tester |
Unfortunately they don't make 5V zeners - only 4.7V or 5.1V.
The turnoff voltage is also affected by the actual dropout current of the relay
as well. The less current it takes to hold in the relay, the lower the voltage
it drops out at. And conversely, the
higher the current it takes to hold the relay on, the higher the voltage it drops
out at.
The gain of the 2N3904 also affects the turnoff voltage as well as the actual resistor
values.
However, none of these should make a huge difference.
If you have a variable power supply you can experiment and check things. If not,
you will just have to try various different components.
Do NOT change the top 470 ohm resistor very much. If you reduce it too much you
will burn out the transistor or zener.
With the circuit elements shown the nominal turnoff voltage should be ~10.5V.
Finally, how do you know that it turned off at 12V? The only real way to know this
is to watch it with a voltmeter WHEN the circuit turns off. If you go back
later to check things after the circuit
turned off, the battery voltage will have recovered somewhat and it is quite possible
that it will show 12V on a voltmeter when it is sitting there with no load.
Dick Tasker
Charles Davis wrote:
>
> You may have better luck getting 2x5v 1% zeners than a 10v 1% - just wire them
in series
>
> Charles
>
>
> On 31/01/21 03:10 am, Roger Evenson wrote:
>> Bought new resistors and 10V zener. Rewired carefully on a test board. This
time it kicked off, but at a higher voltage than I wanted (12V).
>>
>> The zener was a NTE5019A, 10.0V +/-5%, 1/2 watt. Isn't that more like +/-20%?
Cost all of $0.79.
>>
>> I'll go back Monday, see if I can get a +/-1% zener, and ask about a higher
quality brand.
>>
>> Thanks for your comments. One more question...does the wattage make a difference
in this circuit?
>> Roger.
>>
>
>
Message 2
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I am installing dual lightspeed ignitions in my Bearhawk. 5100H1LC LEDs are speced
as panel mounts to indicate when one of the ignitions is not powered. The
LEDs are powered off a pin on the ignition output connectors. The LEDS are described
as 1.8V low current, the red lead is indicated as positive. To test them
I used a new AA battery reading 1.6V. I did not get even a faint glow, so wondering
if they are bad or if they need the full 1.8V or more to produce visible
output.
Rod
Message 3
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| Subject: | Re: LED question |
The spec says will operate off 5V to 12V without an external resistor". You just need more juice. See datasheet here https://www.digikey.com/en/products/detail/visual-communications-company-vcc/5100H1LC/59900
-Kent
> On Jan 31, 2021, at 1:37 PM, Rod Smith <rodsmith52@yahoo.com> wrote:
>
> I am installing dual lightspeed ignitions in my Bearhawk. 5100H1LC LEDs are speced
as panel mounts to indicate when one of the ignitions is not powered. The
LEDs are powered off a pin on the ignition output connectors. The LEDS are described
as 1.8V low current, the red lead is indicated as positive. To test them
I used a new AA battery reading 1.6V. I did not get even a faint glow, so
wondering if they are bad or if they need the full 1.8V or more to produce visible
output.
>
> Rod
Message 4
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| Subject: | Re: LED question |
Do NOT test an LED with a battery without a series resistor. Otherwise the
LED will be destroyed. You did not destroy yours because the battery voltage
was not high enough. But if the battery was 1.8 volts or more, the LED would
be destroyed without a series resistor. There are online calculators to
determine the resistor value to use.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500483#500483
Message 5
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| Subject: | Re: LED question |
I was wrong and Kent is right. The 5100H1LC has a Built-in resistor chip.
But if an LED does not have a built in resistor, then one must be added.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500484#500484
Message 6
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| Subject: | Re: Poor Man's Battery Tester |
At 10:24 AM 1/31/2021, you wrote:
>Tasker <dick@thetaskerfamily.com>
>
>Unfortunately they don't make 5V zeners - only 4.7V or 5.1V.
>
>The turnoff voltage is also affected by the
>actual dropout current of the relay as
>well.=C2 The less current it takes to hold in the
>relay, the lower the voltage it drops out
>at.=C2 And conversely, the higher the current it
>takes to hold the relay on, the higher the voltage it drops out at.
My apologies guys . . . I intended to update that
article years ago for just problems you're wrestling
with. I sat down today and finished an update that I
started some time ago.
https://tinyurl.com/y44wl64t
The 'sloppy' zener is replaced with a precision
adjustable zener. The test set's trip point is
calibrated by one of two methods. Use precision,
1% resistors to bias up the reference port of the
zener -OR- you can use 5% resistors and a potentiometer
to fabricate an adjustable trip point feature.
Either technique yields a predictable and stable
set point for disconnecting the test load. Again,
please forgive my tardiness.
I'll also remind readers of a sophisticated
battery test option in the form of West Mountain
Radio's CBA series, computer driven battery
testers.
https://tinyurl.com/mas7ea9
The one I have right now is probably the 4th
in a series that I've owned over the last 20
years, give or take. They are versatile and
accurate.
But for most of our brother's need to peek
into Conditions for Continued Airworthiness,
the Po' Man's battery-runner-downer is of
excellent value.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 7
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| Subject: | Re: Poor Man's Battery Tester |
Bob,
Is that the correct symbol for the 1N4001?=C2- Is it a zener?
-Jeff
On Sunday, January 31, 2021, 08:24:34 PM PST, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
At 10:24 AM 1/31/2021, you wrote:
--> AeroElectric-List messageposted by: Dick Tasker <dick@thetaskerfamily.c
om>
Unfortunately they don't make 5V zeners - only 4.7V or 5.1V.
The turnoff voltage is also affected by the actual dropout current of there
lay as well.=C3=82=C2- The less current it takes to hold in the relay, th
elower the voltage it drops out at.=C3=82=C2- And conversely, the higher
thecurrent it takes to hold the relay on, the higher the voltage it dropsou
t at.
=C2- My apologies guys . . . I intended to update that
=C2- article years ago for just problems you're wrestling
=C2- with. I sat down today and finished an update that I
=C2- started some time ago.
https://tinyurl.com/y44wl64t
=C2- The 'sloppy' zener is replaced with a precision
=C2- adjustable zener. The test set's trip point is
=C2- calibrated by one of two methods. Use precision,
=C2- 1% resistors to bias up the reference port of the
=C2- zener -OR- you can use 5% resistors and a potentiometer
=C2- to fabricate an adjustable trip point feature.
=C2- Either technique yields a predictable and stable
=C2- set point for disconnecting the test load. Again,
=C2- please forgive my tardiness.
=C2- I'll also remind readers of a sophisticated
=C2- battery test option in the form of West Mountain
=C2- Radio's CBA series, computer driven battery
=C2- testers.
https://tinyurl.com/mas7ea9
=C2- The one I have right now is probably the 4th
=C2- in a series that I've owned over the last 20
=C2- years, give or take. They are versatile and
=C2- accurate.
=C2- But for most of our brother's need to peek
=C2- into Conditions for Continued Airworthiness,
=C2- the Po' Man's battery-runner-downer is of
=C2- excellent value.
=C2- Bob . . .
=C2- Un impeachable logic: George Carlin asked, "If blackboxes
=C2- survive crashes, why don't they make the whole airplane
=C2- out of that stuff?"
Message 8
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| Subject: | Re: Poor Man's Battery Tester |
and do you need the second 470 ohm resistor between the transistor base &
the LM431?
-Jeff
On Sunday, January 31, 2021, 10:18:10 PM PST, Jeff Luckey <jluckey@pacb
ell.net> wrote:
Bob,
Is that the correct symbol for the 1N4001?=C2- Is it a zener?
-Jeff
On Sunday, January 31, 2021, 08:24:34 PM PST, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
At 10:24 AM 1/31/2021, you wrote:
--> AeroElectric-List messageposted by: Dick Tasker <dick@thetaskerfamily.c
om>
Unfortunately they don't make 5V zeners - only 4.7V or 5.1V.
The turnoff voltage is also affected by the actual dropout current of there
lay as well.=C3=82=C2- The less current it takes to hold in the relay, th
elower the voltage it drops out at.=C3=82=C2- And conversely, the higher
thecurrent it takes to hold the relay on, the higher the voltage it dropsou
t at.
=C2- My apologies guys . . . I intended to update that
=C2- article years ago for just problems you're wrestling
=C2- with. I sat down today and finished an update that I
=C2- started some time ago.
https://tinyurl.com/y44wl64t
=C2- The 'sloppy' zener is replaced with a precision
=C2- adjustable zener. The test set's trip point is
=C2- calibrated by one of two methods. Use precision,
=C2- 1% resistors to bias up the reference port of the
=C2- zener -OR- you can use 5% resistors and a potentiometer
=C2- to fabricate an adjustable trip point feature.
=C2- Either technique yields a predictable and stable
=C2- set point for disconnecting the test load. Again,
=C2- please forgive my tardiness.
=C2- I'll also remind readers of a sophisticated
=C2- battery test option in the form of West Mountain
=C2- Radio's CBA series, computer driven battery
=C2- testers.
https://tinyurl.com/mas7ea9
=C2- The one I have right now is probably the 4th
=C2- in a series that I've owned over the last 20
=C2- years, give or take. They are versatile and
=C2- accurate.
=C2- But for most of our brother's need to peek
=C2- into Conditions for Continued Airworthiness,
=C2- the Po' Man's battery-runner-downer is of
=C2- excellent value.
=C2- Bob . . .
=C2- Un impeachable logic: George Carlin asked, "If blackboxes
=C2- survive crashes, why don't they make the whole airplane
=C2- out of that stuff?"
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