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Re: I think I opened a big old can of worms
Approximately 9/10/03 18:09, Jerry Bransford uttered for posterity:
> Electrical noise or sound is AC (alternating current) and a capacitor passes > AC and blocks DC. So if you connect a capacitor between the + power lead > and ground, the capacitor will pass the AC noise component riding on the DC > voltage to ground. > > A capacitor with a rating of 25 volts or higher will be fine. Electrolytic > capacitors are the best type for this application... you can tell an > electrolytic capacitor by the leads being marked + and -. The bigger the > capacitor, the better filtration it provides. > Polarized electrolytics are bypass caps for one direction of flow and rectifiers in the other. A quick and dirty way to solve this is to parallel two with leads reversed... and oddly enough you can also series connect them with the two negative leads, but you get half the capacitance. Personally I'd go for 2.5 times max voltage which gets closer to 50 volt than 24, with 100 volts not being overkill. And normally recommend bypassing any electrolytic with a .01 or so mylar, etc. |
Re: I think I opened a big old can of worms
Jerry Bransford wrote:
> Electrical noise or sound is AC (alternating current) and a capacitor passes > AC and blocks DC. So if you connect a capacitor between the + power lead > and ground, the capacitor will pass the AC noise component riding on the DC > voltage to ground. > > A capacitor with a rating of 25 volts or higher will be fine. Electrolytic > capacitors are the best type for this application... you can tell an > electrolytic capacitor by the leads being marked + and -. The bigger the > capacitor, the better filtration it provides. Have the same annoying alternator whine. I ordered a couple solutions from David Navone Engineering on the web. Haven't isntalled the more expensive filter yet, but the inline antenna isolator was a complete bust. > > Jerry > -- > Jerry Bransford > To email, remove 'me' from my email address > KC6TAY, PP-ASEL > See the Geezer Jeep at > http://members.cox.net/jerrypb/ > > "Michael Vincenty" <mvincenty@adelphia.net> wrote in message > news:AOP7b.41445$Nc.10104269@news1.news.adelphia.n et... > >>Hey, maybe you can offer me a bit of assistance on a similar problem (not > > a > >>Jeep - sorry). I too have been trouble-shooting a similar problem with an >>89 GMC C1500 which has an alternator whine coming from the radio (changes >>with engine RPMs). >> >>The factory service manual says to try and install a 250 MFD (100 V) >>capacitor on the alternator output lead and/or brown field wire to the >>ground. I tried this and it did not work. If I am reading your post >>correctly, you are recommending installing a .1 microfarad capacitor on > > the > >>battery postive lead into the radio and ground (as close as possible to > > the > >>radio as possible). Is that correct? Does voltage matter as long as it > > is > >>at least 12 volts? Do you know how installing a capacitor works to >>eliminate the whine (just was wondering)? >> >>Thanks >> >>mpv >> >>BTW, the alternator has been replaced several times, and the problem still >>exists, so I know that it shouldn't be the alternator. >>"A.H. MacIntosh aka USERNAME" <chesshire_cat@nospam.net> wrote in message >>news:TiK7b.8160$cQ1.2327231@kent.svc.tds.net.. . >> >>>Easiest way to eliminate non-RF electrical noise (at least that I have >>>found) is to use a .1uf mylar cap to ground from the B+ line. It helps > > to > >>>add one at the closest practical point to the radio, and others at the >>>offending devices (motors/alternators) be sure to restrain the cap >> >>properly, >> >>>and insulate the leads. >>> >>> >>>Not perfect, but simple, and eliminates most noise sources. >>> >>>tach picks up signal from switched side of coil. >>> >>>"Foot Loose" <footloose61@ NOSPAM hotmail.com> wrote in message >>>news:NGw7b.7831$cQ1.2249605@kent.svc.tds.net. .. >>> >>>>I have been having a lot of problems with a whining noise in my radio >> >>and >> >>>>CB. I've put a filter on the power lines and hooked it directly to the >>>>battery with no luck. So being the "I want to fix it all" type of guy, > > I > >>>>started looking under the hood for a bad ground. Well I have replaced >> >>the >> >>>>engine, carb, distributor, and gotten rid of all the emissions stuff >> >>and >> >>>>there were a lot of connectors tie rapped to the fire wall where I > > left > >>>them >>> >>>>after disconnecting them. Well I started to pull the unused wires out. >>> >>>After >>> >>>>3 hours and a couple of dozen wires the Jeep started. The only problem >> >>is >> >>>>the Tac will not work, so here are my questions: >>>> >>>>Where does the tac get its signal from? >>>> >>>>What are the 2 relays, 2 capped connectors, and 4 wire circuit board >> >>that >> >>>>are between the fender and the battery? >>>> >>>>Next I want to go under the dash and remove the computer and all the >> >>crap >> >>>>under there, what is the easiest way to get it out?? >>>> >>>>Well I'm back to it tomorrow, thanks in advance for all advice. >>>> >>>>Scott >>>>90YJ >>>>4.2L AX15 >>>> >>>> >>> >>> >> > > |
Re: I think I opened a big old can of worms
Jerry Bransford wrote:
> Electrical noise or sound is AC (alternating current) and a capacitor passes > AC and blocks DC. So if you connect a capacitor between the + power lead > and ground, the capacitor will pass the AC noise component riding on the DC > voltage to ground. > > A capacitor with a rating of 25 volts or higher will be fine. Electrolytic > capacitors are the best type for this application... you can tell an > electrolytic capacitor by the leads being marked + and -. The bigger the > capacitor, the better filtration it provides. Have the same annoying alternator whine. I ordered a couple solutions from David Navone Engineering on the web. Haven't isntalled the more expensive filter yet, but the inline antenna isolator was a complete bust. > > Jerry > -- > Jerry Bransford > To email, remove 'me' from my email address > KC6TAY, PP-ASEL > See the Geezer Jeep at > http://members.cox.net/jerrypb/ > > "Michael Vincenty" <mvincenty@adelphia.net> wrote in message > news:AOP7b.41445$Nc.10104269@news1.news.adelphia.n et... > >>Hey, maybe you can offer me a bit of assistance on a similar problem (not > > a > >>Jeep - sorry). I too have been trouble-shooting a similar problem with an >>89 GMC C1500 which has an alternator whine coming from the radio (changes >>with engine RPMs). >> >>The factory service manual says to try and install a 250 MFD (100 V) >>capacitor on the alternator output lead and/or brown field wire to the >>ground. I tried this and it did not work. If I am reading your post >>correctly, you are recommending installing a .1 microfarad capacitor on > > the > >>battery postive lead into the radio and ground (as close as possible to > > the > >>radio as possible). Is that correct? Does voltage matter as long as it > > is > >>at least 12 volts? Do you know how installing a capacitor works to >>eliminate the whine (just was wondering)? >> >>Thanks >> >>mpv >> >>BTW, the alternator has been replaced several times, and the problem still >>exists, so I know that it shouldn't be the alternator. >>"A.H. MacIntosh aka USERNAME" <chesshire_cat@nospam.net> wrote in message >>news:TiK7b.8160$cQ1.2327231@kent.svc.tds.net.. . >> >>>Easiest way to eliminate non-RF electrical noise (at least that I have >>>found) is to use a .1uf mylar cap to ground from the B+ line. It helps > > to > >>>add one at the closest practical point to the radio, and others at the >>>offending devices (motors/alternators) be sure to restrain the cap >> >>properly, >> >>>and insulate the leads. >>> >>> >>>Not perfect, but simple, and eliminates most noise sources. >>> >>>tach picks up signal from switched side of coil. >>> >>>"Foot Loose" <footloose61@ NOSPAM hotmail.com> wrote in message >>>news:NGw7b.7831$cQ1.2249605@kent.svc.tds.net. .. >>> >>>>I have been having a lot of problems with a whining noise in my radio >> >>and >> >>>>CB. I've put a filter on the power lines and hooked it directly to the >>>>battery with no luck. So being the "I want to fix it all" type of guy, > > I > >>>>started looking under the hood for a bad ground. Well I have replaced >> >>the >> >>>>engine, carb, distributor, and gotten rid of all the emissions stuff >> >>and >> >>>>there were a lot of connectors tie rapped to the fire wall where I > > left > >>>them >>> >>>>after disconnecting them. Well I started to pull the unused wires out. >>> >>>After >>> >>>>3 hours and a couple of dozen wires the Jeep started. The only problem >> >>is >> >>>>the Tac will not work, so here are my questions: >>>> >>>>Where does the tac get its signal from? >>>> >>>>What are the 2 relays, 2 capped connectors, and 4 wire circuit board >> >>that >> >>>>are between the fender and the battery? >>>> >>>>Next I want to go under the dash and remove the computer and all the >> >>crap >> >>>>under there, what is the easiest way to get it out?? >>>> >>>>Well I'm back to it tomorrow, thanks in advance for all advice. >>>> >>>>Scott >>>>90YJ >>>>4.2L AX15 >>>> >>>> >>> >>> >> > > |
Re: I think I opened a big old can of worms
Cal Wheeler wrote:
> Jerry Bransford wrote: > >> Electrical noise or sound is AC (alternating current) and a capacitor passes >> AC and blocks DC. So if you connect a capacitor between the + power lead >> and ground, the capacitor will pass the AC noise component riding on the DC >> voltage to ground. Kinda sorta. All depends on how the cap is set up. + >------||------> DC blocking (commonly used in amplifiers) - >--------------> But this is usually not an electrolytic + >---.----------> AC blocking (also used to provide | + - a reserve for large sterio systems `--|(--. using some serious capacitors) | - >----------'---> Elimination of whine (because of the high frequency) is easier with a ferrous choke or coil. Here is a quick thing to try. Go to RadioShack and get a clip on ferrous choke for an AC cord, clip it on the battery to alternator connection and see if it helps. If not, just take it back. (ps) Never tried this myself. The other option is to use a ferrous donut. You wind the power and ground feed for your radio around the donut (through the hole). Probably 8-9 windings should be sufficient. Just some ideas. -- DougW |
Re: I think I opened a big old can of worms
Cal Wheeler wrote:
> Jerry Bransford wrote: > >> Electrical noise or sound is AC (alternating current) and a capacitor passes >> AC and blocks DC. So if you connect a capacitor between the + power lead >> and ground, the capacitor will pass the AC noise component riding on the DC >> voltage to ground. Kinda sorta. All depends on how the cap is set up. + >------||------> DC blocking (commonly used in amplifiers) - >--------------> But this is usually not an electrolytic + >---.----------> AC blocking (also used to provide | + - a reserve for large sterio systems `--|(--. using some serious capacitors) | - >----------'---> Elimination of whine (because of the high frequency) is easier with a ferrous choke or coil. Here is a quick thing to try. Go to RadioShack and get a clip on ferrous choke for an AC cord, clip it on the battery to alternator connection and see if it helps. If not, just take it back. (ps) Never tried this myself. The other option is to use a ferrous donut. You wind the power and ground feed for your radio around the donut (through the hole). Probably 8-9 windings should be sufficient. Just some ideas. -- DougW |
Re: I think I opened a big old can of worms
Approximately 9/11/03 04:33, DougW uttered for posterity:
> Cal Wheeler wrote: >> Jerry Bransford wrote: >> >>> Electrical noise or sound is AC (alternating current) and a capacitor passes >>> AC and blocks DC. So if you connect a capacitor between the + power lead >>> and ground, the capacitor will pass the AC noise component riding on the DC >>> voltage to ground. > > Kinda sorta. All depends on how the cap is set up. + >------||------> DC blocking (commonly used in amplifiers) - >--------------> But this is usually not an electrolytic + >---.----------> AC blocking (also used to provide | + - a reserve for large sterio systems `--|(--. using some serious capacitors) | - >----------'---> The problem with the last one is that a typical electrolytic is a lousy high frequency bypass. Thats why they are normally bypassed with a small mylar or such. To nit-pick, that is not an AC blocking arrangement, it is a low frequency bypass arrangement. > > Elimination of whine (because of the high frequency) is easier with > a ferrous choke or coil. > > Here is a quick thing to try. Go to RadioShack and get a clip on > ferrous choke for an AC cord, clip it on the battery to alternator > connection and see if it helps. If not, just take it back. > (ps) Never tried this myself. > > The other option is to use a ferrous donut. You wind the power and > ground feed for your radio around the donut (through the hole). > Probably 8-9 windings should be sufficient. The clamp-ons and donuts work best if you use them with a capacitor to ground. Stealing your drawing... + >---.--------------MMMMMMMM-----> | + - `--|(--. | - >----------'---> The choke adds resistance to the high frequencies causing the noise, but unless you also have a low resistance path to ground for the noise, you don't bypass as effectively. The ferrous donuts will need to be fairly physically large, and you really would only need a turn or so thru it. Probably cheaper to buy commercial bypass filters and stick them everywhere. And unhook the antenna which is a common source of noise while testing. |
Re: I think I opened a big old can of worms
Approximately 9/11/03 04:33, DougW uttered for posterity:
> Cal Wheeler wrote: >> Jerry Bransford wrote: >> >>> Electrical noise or sound is AC (alternating current) and a capacitor passes >>> AC and blocks DC. So if you connect a capacitor between the + power lead >>> and ground, the capacitor will pass the AC noise component riding on the DC >>> voltage to ground. > > Kinda sorta. All depends on how the cap is set up. + >------||------> DC blocking (commonly used in amplifiers) - >--------------> But this is usually not an electrolytic + >---.----------> AC blocking (also used to provide | + - a reserve for large sterio systems `--|(--. using some serious capacitors) | - >----------'---> The problem with the last one is that a typical electrolytic is a lousy high frequency bypass. Thats why they are normally bypassed with a small mylar or such. To nit-pick, that is not an AC blocking arrangement, it is a low frequency bypass arrangement. > > Elimination of whine (because of the high frequency) is easier with > a ferrous choke or coil. > > Here is a quick thing to try. Go to RadioShack and get a clip on > ferrous choke for an AC cord, clip it on the battery to alternator > connection and see if it helps. If not, just take it back. > (ps) Never tried this myself. > > The other option is to use a ferrous donut. You wind the power and > ground feed for your radio around the donut (through the hole). > Probably 8-9 windings should be sufficient. The clamp-ons and donuts work best if you use them with a capacitor to ground. Stealing your drawing... + >---.--------------MMMMMMMM-----> | + - `--|(--. | - >----------'---> The choke adds resistance to the high frequencies causing the noise, but unless you also have a low resistance path to ground for the noise, you don't bypass as effectively. The ferrous donuts will need to be fairly physically large, and you really would only need a turn or so thru it. Probably cheaper to buy commercial bypass filters and stick them everywhere. And unhook the antenna which is a common source of noise while testing. |
Re: I think I opened a big old can of worms
I use a Mylar cap, I seem to remember 600V, but that was only because it was
a junk box item. anything over 100V is great. One at the radio, and another (if needed) at the alt output. (the one at alt is to catch any RF before it uses the lead as an aerial. the cap passes AC/pulse dc (aka whine) to ground. "Michael Vincenty" <mvincenty@adelphia.net> wrote in message news:AOP7b.41445$Nc.10104269@news1.news.adelphia.n et... > Hey, maybe you can offer me a bit of assistance on a similar problem (not a > Jeep - sorry). I too have been trouble-shooting a similar problem with an > 89 GMC C1500 which has an alternator whine coming from the radio (changes > with engine RPMs). > > The factory service manual says to try and install a 250 MFD (100 V) > capacitor on the alternator output lead and/or brown field wire to the > ground. I tried this and it did not work. If I am reading your post > correctly, you are recommending installing a .1 microfarad capacitor on the > battery postive lead into the radio and ground (as close as possible to the > radio as possible). Is that correct? Does voltage matter as long as it is > at least 12 volts? Do you know how installing a capacitor works to > eliminate the whine (just was wondering)? > > Thanks > > mpv > > BTW, the alternator has been replaced several times, and the problem still > exists, so I know that it shouldn't be the alternator. > "A.H. MacIntosh aka USERNAME" <chesshire_cat@nospam.net> wrote in message > news:TiK7b.8160$cQ1.2327231@kent.svc.tds.net... > > Easiest way to eliminate non-RF electrical noise (at least that I have > > found) is to use a .1uf mylar cap to ground from the B+ line. It helps to > > add one at the closest practical point to the radio, and others at the > > offending devices (motors/alternators) be sure to restrain the cap > properly, > > and insulate the leads. > > > > > > Not perfect, but simple, and eliminates most noise sources. > > > > tach picks up signal from switched side of coil. > > > > "Foot Loose" <footloose61@ NOSPAM hotmail.com> wrote in message > > news:NGw7b.7831$cQ1.2249605@kent.svc.tds.net... > > > I have been having a lot of problems with a whining noise in my radio > and > > > CB. I've put a filter on the power lines and hooked it directly to the > > > battery with no luck. So being the "I want to fix it all" type of guy, I > > > started looking under the hood for a bad ground. Well I have replaced > the > > > engine, carb, distributor, and gotten rid of all the emissions stuff > and > > > there were a lot of connectors tie rapped to the fire wall where I left > > them > > > after disconnecting them. Well I started to pull the unused wires out. > > After > > > 3 hours and a couple of dozen wires the Jeep started. The only problem > is > > > the Tac will not work, so here are my questions: > > > > > > Where does the tac get its signal from? > > > > > > What are the 2 relays, 2 capped connectors, and 4 wire circuit board > that > > > are between the fender and the battery? > > > > > > Next I want to go under the dash and remove the computer and all the > crap > > > under there, what is the easiest way to get it out?? > > > > > > Well I'm back to it tomorrow, thanks in advance for all advice. > > > > > > Scott > > > 90YJ > > > 4.2L AX15 > > > > > > > > > > > > |
Re: I think I opened a big old can of worms
I use a Mylar cap, I seem to remember 600V, but that was only because it was
a junk box item. anything over 100V is great. One at the radio, and another (if needed) at the alt output. (the one at alt is to catch any RF before it uses the lead as an aerial. the cap passes AC/pulse dc (aka whine) to ground. "Michael Vincenty" <mvincenty@adelphia.net> wrote in message news:AOP7b.41445$Nc.10104269@news1.news.adelphia.n et... > Hey, maybe you can offer me a bit of assistance on a similar problem (not a > Jeep - sorry). I too have been trouble-shooting a similar problem with an > 89 GMC C1500 which has an alternator whine coming from the radio (changes > with engine RPMs). > > The factory service manual says to try and install a 250 MFD (100 V) > capacitor on the alternator output lead and/or brown field wire to the > ground. I tried this and it did not work. If I am reading your post > correctly, you are recommending installing a .1 microfarad capacitor on the > battery postive lead into the radio and ground (as close as possible to the > radio as possible). Is that correct? Does voltage matter as long as it is > at least 12 volts? Do you know how installing a capacitor works to > eliminate the whine (just was wondering)? > > Thanks > > mpv > > BTW, the alternator has been replaced several times, and the problem still > exists, so I know that it shouldn't be the alternator. > "A.H. MacIntosh aka USERNAME" <chesshire_cat@nospam.net> wrote in message > news:TiK7b.8160$cQ1.2327231@kent.svc.tds.net... > > Easiest way to eliminate non-RF electrical noise (at least that I have > > found) is to use a .1uf mylar cap to ground from the B+ line. It helps to > > add one at the closest practical point to the radio, and others at the > > offending devices (motors/alternators) be sure to restrain the cap > properly, > > and insulate the leads. > > > > > > Not perfect, but simple, and eliminates most noise sources. > > > > tach picks up signal from switched side of coil. > > > > "Foot Loose" <footloose61@ NOSPAM hotmail.com> wrote in message > > news:NGw7b.7831$cQ1.2249605@kent.svc.tds.net... > > > I have been having a lot of problems with a whining noise in my radio > and > > > CB. I've put a filter on the power lines and hooked it directly to the > > > battery with no luck. So being the "I want to fix it all" type of guy, I > > > started looking under the hood for a bad ground. Well I have replaced > the > > > engine, carb, distributor, and gotten rid of all the emissions stuff > and > > > there were a lot of connectors tie rapped to the fire wall where I left > > them > > > after disconnecting them. Well I started to pull the unused wires out. > > After > > > 3 hours and a couple of dozen wires the Jeep started. The only problem > is > > > the Tac will not work, so here are my questions: > > > > > > Where does the tac get its signal from? > > > > > > What are the 2 relays, 2 capped connectors, and 4 wire circuit board > that > > > are between the fender and the battery? > > > > > > Next I want to go under the dash and remove the computer and all the > crap > > > under there, what is the easiest way to get it out?? > > > > > > Well I'm back to it tomorrow, thanks in advance for all advice. > > > > > > Scott > > > 90YJ > > > 4.2L AX15 > > > > > > > > > > > > |
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