Return-Path: Received: from [199.185.220.240] (HELO priv-edtnes57.telusplanet.net) by logan.com (CommuniGate Pro SMTP 4.1.1) with ESMTP id 2536962 for flyrotary@lancaironline.net; Thu, 21 Aug 2003 19:33:58 -0400 Received: from Endurance ([209.53.248.89]) by priv-edtnes57.telusplanet.net (InterMail vM.5.01.05.17 201-253-122-126-117-20021021) with SMTP id <20030821233335.MBBP27176.priv-edtnes57.telusplanet.net@Endurance> for ; Thu, 21 Aug 2003 17:33:35 -0600 From: "Haywire" To: "Rotary motors in aircraft" Subject: tach divider Date: Thu, 21 Aug 2003 16:33:35 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0023_01C36801.F76E1AB0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0023_01C36801.F76E1AB0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi Finn; You got me thinking that I could come up with a better solution, than a voltage divider. I built the circuit on a breadboard again, but using a capacitor across VDD & VSS this time. I tried various capacitors and was unable to improve on the stability at higher voltages without a voltage divider. I was considering ordering a couple of regulators (still the best idea) when I started considering that I really don't know anything about the output pulse from the EC2 other than it is a 12pulse/rev signal. So I borrowed a Fluke scope from our shop and brought it to the airport to have a look at the wave. It is a square wave 768mV peak to peak, base voltage 8mV (I guess I could have just asked Tracy :-). This surprised me as I was expecting 5V. In experiments on the breadboard I found that the counter performed well at voltages up to 20V as long as the clock input was not greater than 5 volts below supply voltage. Now it's becoming a little more clear (remember, I'm just an apprentice). When I showed the waveform to a journeyman at work, he also was so surprised, he suspects it's not correct. Tracy can you confirm this P/P voltage? The voltage divider, while being a little crude, is effective, so I may just stick with that, unless I can find a couple of 5V regulators in the spare parts. Since I expect that once the EM2 becomes available, most builders will chose to use that since it really is a great tool, so there won't be any reason to get too carried away with this thing. Besides I'm just giving the darned things away because I had 24 extra counter chips, so I shouldn't start buying parts -- no wonder I can never save any money :-) John and Dave; I'll try to get a couple sent off before next week. John, I'll need an address. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely believe in, Enthusiastically act upon, Must inevitably come to pass". -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Finn Lassen Sent: Wednesday, August 20, 2003 5:41 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: some progress, and more understanding A capacitor accross the supply pins should be fine there. I was thinking about the input. Of course if your input comes from Tracy's controller, that's probably not an issue. But from anywhere else, like coil pick up, some input filtering/clamping would be wise. Finn Haywire wrote: Hi Finn; It is a CMOS device capable of handling 20vdc on its VDD pin. So I didn't feel it was necessary. In reality I found it was unstable when VDD was less than 5vdc or greater than 11vdc, so since I had a bag of 470ohm resistors handy, I just put a voltage divider on the VDD. With a regulated 13.8vdc it gives me just under 7 volts and a stable reading. a side note; I originally had an internally regulated alternator but the regulator failed (have since converted to an external reg as per "electric Bob"). When running with the alternator tripped and less than 12vdc, I found the tach would become erratic at high RPM's, due to a low VDD. When alt is charging, everything is fine. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely believe in, Enthusiastically act upon, Must inevitably come to pass". -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Finn Lassen Sent: Tuesday, August 19, 2003 8:23 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: some progress, and more understanding I don't see a Zener diode to clamp any spikes. Finn Haywire wrote: Attached are a couple of pics of my tach divider. It can be set to divide by any number necessary. I can't guarantee it would work with any tach but it works very well with my cheap off-the-shelf-at-any-autoparts-store, Hastings tach. I have a few more if anybody wants one. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely believe in, Enthusiastically act upon, Must inevitably come to pass". The EC-2 tach output has 12 pulses per revolution, and won't directly work with any normal tach. Todd has made a divider to bring the pulse rate down to normal, and it sounds like it's working well. The TT that you have expects 1 pulse per rev, so if you don't mind dividing the rpm reading by 12... :-) ------=_NextPart_000_0023_01C36801.F76E1AB0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Hi=20 Finn;
    You got me thinking that I could come up with a = better=20 solution, than a voltage divider. I built the circuit on a breadboard = again, but=20 using a capacitor across VDD & VSS this time. I tried various = capacitors and=20 was unable to improve on the stability at higher voltages without a = voltage=20 divider. I was considering ordering a couple of regulators (still the = best idea)=20 when I started considering that I really don't know anything about the = output=20 pulse from the EC2 other than it is a 12pulse/rev signal. So I borrowed = a Fluke=20 scope from our shop and brought it to the airport to have a look at the = wave. It=20 is a square wave 768mV peak to peak, base voltage 8mV (I guess I could = have just=20 asked Tracy :-). This surprised me as I was expecting 5V. In experiments = on the=20 breadboard I found that the counter performed well at voltages up to 20V = as long=20 as the clock input was not greater than 5 volts below supply = voltage.=20 Now it's becoming a little more clear (remember, I'm just an = apprentice). When I=20 showed the waveform to a journeyman at work, he also was so surprised, = he=20 suspects it's not correct. Tracy can you confirm this P/P=20 voltage?
    The voltage divider, while being a little = crude, is=20 effective, so I may just stick with that, unless I can find a couple of = 5V=20 regulators in the spare parts. Since I expect that once the EM2 becomes=20 available, most builders will chose to use that since it really is a = great tool,=20 so there won't be any reason to get too carried away with this thing. = Besides=20 I'm just giving the darned things away because I had 24 extra counter = chips, so=20 I shouldn't start buying parts -- no wonder I can never save any money=20 :-)
 
John=20 and Dave;
    I'll try to get a couple sent off before = next week.=20 John, I'll need an address.
 

S. Todd Bartrim
Turbo 13B = RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely believe in,=20 Enthusiastically act upon, Must inevitably come to pass".

-----Original Message-----
From: Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net]On Behalf Of Finn=20 Lassen
Sent: Wednesday, August 20, 2003 5:41 = AM
To: Rotary=20 motors in aircraft
Subject: [FlyRotary] Re: some progress, = and more=20 understanding

A capacitor accross the supply pins = should=20 be fine there. I was thinking about the input. Of course if your input = comes=20 from Tracy's controller, that's probably not an issue. But from = anywhere else,=20 like coil pick up, some input filtering/clamping would be=20 wise.

Finn

Haywire wrote:
Hi=20 Finn;
    It is a CMOS device capable of handling = 20vdc on its=20 VDD pin. So I didn't feel it was necessary. In reality I found it = was=20 unstable when VDD was less than 5vdc or greater than 11vdc, so since = I had a=20 bag of 470ohm resistors handy, I just put a voltage divider on the = VDD. With=20 a regulated 13.8vdc it gives me just under 7 volts and a stable = reading.=20
    a side note; I originally had an = internally=20 regulated alternator but the regulator failed (have since converted = to an=20 external reg as per "electric Bob"). When running with the = alternator=20 tripped and less than 12vdc, I found the tach would become erratic = at high=20 RPM's, due to a low VDD. When alt is charging, everything is=20 fine.
 

S. Todd Bartrim
Turbo 13B = RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely believe = in,=20 Enthusiastically act upon, Must inevitably come to pass". =

-----Original Message-----
From: Rotary motors = in=20 aircraft [mailto:flyrotary@lancaironlin= e.net]On=20 Behalf Of Finn Lassen
Sent: Tuesday, August 19, 2003 = 8:23=20 PM
To: Rotary motors in aircraft
Subject: = [FlyRotary]=20 Re: some progress, and more understanding

I = don't see=20 a Zener diode to clamp any spikes.

Finn

Haywire = wrote:
Attached are a couple of pics of my = tach=20 divider. It can be set to divide by any number necessary. I = can't=20 guarantee it would work with any tach but it works very well = with my=20 cheap off-the-shelf-at-any-autoparts-store, Hastings tach. I = have a few=20 more if anybody wants one.
 

S. Todd Bartrim
Turbo 13B=20 RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely = believe in,=20 Enthusiastically act upon, Must inevitably come to pass". =

 
The EC-2 tach=20 output has 12 pulses per revolution, and won't directly work = with any=20 normal tach.  Todd has made a divider to bring the pulse = rate=20 down to normal, and it sounds like it's working well.  = The TT=20 that you have expects 1 pulse per rev, so if you don't mind = dividing=20 the rpm reading by 12...  :-)
=

 


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