X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Tue, 01 Dec 2009 06:31:04 -0500 Message-ID: X-Original-Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTP id 3994758 for lml@lancaironline.net; Sun, 29 Nov 2009 15:04:56 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=dfs155@roadrunner.com Received: from dan ([76.178.186.181]) by cdptpa-omta02.mail.rr.com with SMTP id <20091129200422163.WKSG20286@cdptpa-omta02.mail.rr.com> for ; Sun, 29 Nov 2009 20:04:22 +0000 X-Original-Message-ID: <7B7C92F9B470421EA99688F74AA9E88E@dan> From: "Dan Schaefer" X-Original-To: "Lancair list" Subject: Fw: Gear warning indicator X-Original-Date: Sun, 29 Nov 2009 12:04:18 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0014_01CA70EC.1419D330" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0014_01CA70EC.1419D330 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I have many errors (just ask my wife) but not in referring to every Lancair= and in every case, as you do. Many have the bulbs grounded with the gear s= witches providing 12 v when closed to illuminate said bulbs (down and locke= d), substantiating my earlier post. Early builder's manuals (back when they= were in monthly flux and the illustrations were hand-drawn) had a suggeste= d circuit diagram showing it this way and I'll bet most builders back then = wired the system just that way - I know I did, and for a couple of reasons.= One, so my indicator lights (all of them, not just the gear lights) could = use a simple =22press to test=22 circuit from a single button, and two, simple = failure analysis said that it is slightly safer to run the bus voltage to t= he switches so the rest of the wiring, during flight, was effectively at gr= ound via the bulbs. If you didn't know this, I'll see your' snide comment and raise you ten. Dan Schaefer Early LNC-2 ----- Original Message ----- From: Wolfgang To: lml Sent: Saturday, November 28, 2009 9:54 AM Subject: Gear warning indicator Hmmm . . . The gear position switches provide a GROUND to the bulbs. If on= e or more of the lights are lit by a gear position switch, the voltage at t= hat side (my diodes) of the bulb is GROUND which can not feed any voltage b= ack to the circuit. Look again and hopefully you will see the error of your ways. Wolfgang ---------------------------------------------------------------------------= ----- From: =22Dan Schaefer=22 Sender: Subject: Gear warning indicator Date: Fri, 27 Nov 2009 08:40:07 -0500 To: lml Excuse me!! This looks to have at least two design faults. Problem 1: If the airspeed switch is closed and any one (or more) of = the green =22down and locked=22 lights are energized via the gear position swit= ches, 12 volts will be applied thru one or more of the diodes to this =22blin= ker=22 and it will try to operate - e.g., the 1000 mike capacitor will charge= thru the 100 ohm resistor until the voltage reaches the relay pull-in volt= age. Problem 2: Unfortunately, as soon as the capacitor charges sufficient= ly to pull in the relay, the relay contacts close and the 12 volts is short= ed directly to ground. Hopefully, only blowing a fuse or popping a breaker,= but effectively taking at least the gear light circuit down. Neat! Dan Schaefer PS: Stick the resistor on the other side of the relay contacts to at = least solve the shorting - not sure what to do to keep this thing from blin= king the lights when at least one gear leg is down and locked. But what do = I know=3F I'm just a retired EE and things have a way of getting fuzzy in 10 = years! DS -- -- I am using the free version of SPAMfighter. We are a community of 6 million users fighting spam. SPAMfighter has removed 632 of my spam emails to date. Get the free SPAMfighter here: http://www.spamfighter.com/len The Professional version does not have this message ------=_NextPart_000_0014_01CA70EC.1419D330 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I have many errors (just ask my wife) but not in referring to every La= ncair and in every case, as you do. Many have the bulbs grounded with the gear switches providing 12 v when closed to illuminate said bulbs (down and lock= ed), substantiating my earlier post. Early builder's manuals (back when they were in monthly flux and the illustrations were hand-drawn) = had a suggested circuit diagram showing it this way and I'll bet most builders ba= ck then wired the system just that way - I know I did, and for a couple of rea= sons. One, so my indicator lights (all of them, not just the gear lights) could u= se a simple =22press to test=22 circuit from a single button, and two, simple failur= e analysis said that it is slightly safer to run the bus voltage to the switc= hes so the rest of the wiring, during flight, was effectively at ground via the= bulbs.
 
If you didn't know this, I'll see your' snide comment and raise you ten.
 
Dan Schaefer
Early LNC-2
 
----- Original Message -----
From: Wolfgang
To: lml
Sent: Saturday, November 28, 2009 9:54 AM
Subject: Gear warning indicator

Hmmm . . .  The gear position switches provide a GROUND to the bu= lbs. If one or more of the lights are lit by a gear position switch, the voltage= at that side (my diodes) of the bulb is GROUND which can not feed any voltage = back to the circuit.
 
Look again and hopefully you will see the error of your ways.
 
Wolfgang

 
=
From: =22Dan Schaefer=22 <dfs155@roadrunner.com>
Sender: <marv@lancaironline.net>
Subject: Gear warning indicator
Date: Fri, 27 Nov 2009 08:40:07 -0500
To: lml

 
Excuse me!! This looks to have at least two design faults.

Problem 1: If the airspeed switch is closed and= any one (or more) of the green =22down and locked=22 lights are energized via= the gear position switches, 12 volts will be applied thru one or more of = the diodes to this =22blinker=22 and it will try to operate - e.g., the 1000 = mike capacitor will charge thru the 100 ohm resistor until the voltage rea= ches the relay pull-in voltage.

Problem 2: Unfortunately, as soon a= s the capacitor charges sufficiently to pull in the relay, the relay contac= ts close and the 12 volts is shorted directly to ground. Hopefully, only= blowing a fuse or popping a breaker, but effectively taking at least = the gear light circuit down.

Neat!

Dan Schaefer

PS: = Stick the resistor on the other side of the relay contacts to at least solv= e the shorting - not sure what to do to keep this thing from blinking the l= ights when at least one gear leg is down and locked. But what do I know=3F I'= m just a retired EE and things have a way of getting fuzzy in 10 years!

DS --

I am using the Free version of SPAMfighter.
We are a community of 6 million= users fighting spam.
SPAMfighter has removed 632 of my spam emails to= date.
The Professional version does not have this message.
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