LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #8   Report Post  
 
Posts: n/a
Default Diode question

On Fri, 21 Oct 2005 07:06:49 +0200, "Meindert Sprang"
wrote:

"Tamaroak" wrote in message
...
I have two VHF radios, both of which have a PA and foghorn mode and will
send a 20 watt signal into a horn mounted on my flybridge. Standard
Horizon says I can't just hook the two of them to the same horn becxause
the one radio will backfeed into the other, causing it to be harmed.
The solution is to get two diodes and wire them on the + wire before it
gets to the horn.
Question: What kind, size, specifications do I use for said diode? The
guy at Radio Shack looked at me like I was from Mars, when I asked him

this.
If the horn is 20 Watt and your battery is 12V, you'll need at least a 2 Amp
diode. Ask for a 50V/5A diode and you'll be fine. Higher specs on voltage
and/or current are fine too if that is what is available. The price
difference should be negligent. We're talking about a sub-$ component here.
Meindert


The solution can't work. Who proposed it? Standard? I hope not!

You are making some assumptions here based on the output of the audio amp being
limited to 12 volts. No such limitation exists_ The radio spec will tell you
what the output stage looks like. If the 20watt output rating is into 8 ohms
then it seems unlikely the output is limited to 12 volts. If it is rated into
4ohms the it is 12.

But even still it is likely coupled by a cap or transformer as most speakers
don't handle dc very well_ This makes the diode isolation idea sort of
impossible. Well.... you might put something together to create a bias with a
couple of diodes and some resistors then sum the biased AC the couple the summed
with a cap to the horn/speaker but you are going to loose 50% of your output
power (actually a little more) sort of a foolish way of putting two signals
together and if you thought the simple diode 'or' would work this solution is
probably a bit too difficult.

I suggest picking up one of the auto stereo booster amps_ Get one designed to
take the direct speaker outputs from the stereo and has an output that can be
bridged into a mono amp. Then put one radio to the right channel, one radio to
the left and bridge the horn across the outputs. Hey_ not only will you sum the
outputs of the two radio you'll have a great setup for blaring rap music out of
your fog horn...
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Newbie Question: 40' Performance Cruiser question (including powerplant) charliekilo Cruising 19 October 19th 05 02:30 PM
VOLVO PENTA STARTER MOTOR QUESTION Bob Cruising 0 October 18th 05 01:27 AM
Oil use question Big Pop General 6 October 14th 05 11:02 AM
alternator, voltage regulator question Peter253 Cruising 12 October 14th 05 07:12 AM
Hey Peggie / Group - LactraSan question [email protected] Boat Building 3 October 10th 05 08:37 PM


All times are GMT +1. The time now is 09:53 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 BoatBanter.com.
The comments are property of their posters.
 

About Us

"It's about Boats"

 

Copyright © 2017