---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 01/31/21: 8 ---------------------------------------------------------- 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 _____________________________________ Time: 08:25:49 AM PST US Subject: Re: AeroElectric-List: Poor Man's Battery Tester From: Dick Tasker 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 _____________________________________ Time: 10:38:52 AM PST US From: Rod Smith Subject: AeroElectric-List: LED question 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 _____________________________________ Time: 11:37:33 AM PST US From: Kent or Jackie Ashton Subject: Re: AeroElectric-List: 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 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 _____________________________________ Time: 11:46:04 AM PST US Subject: AeroElectric-List: Re: LED question From: "user9253" 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 _____________________________________ Time: 11:53:11 AM PST US Subject: AeroElectric-List: Re: LED question From: "user9253" 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 _____________________________________ Time: 08:10:35 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Poor Man's Battery Tester At 10:24 AM 1/31/2021, you wrote: >Tasker > >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 _____________________________________ Time: 10:18:53 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: 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 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 _____________________________________ Time: 10:28:50 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: 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 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 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?" ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.