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On 01/12/2024 6:21 AM EST Moose wrote:
>This is brilliant (figuratively AND literally) 8>) But is this safe?
>Couldn't it melt wires if there
>is a short?
Moose,
Yes it's safe if you do it correctly. You want to use a good socket, if it's
not plastic wrap it with electrical tape. We use this for finding a short in a
piece of electronic equipment. Put a 60W light bulb in a box in series with
the outlet that you plug the equipment into. This will limit the current to
1/2 amp.
I also suggest (someone else mentioned this) that you make some sort of adapter
to plug into the fuse socket. For the old
glass cylindrical fuses, solder a piece of insulated wire on each end so you
can connect clip leads to the wire to connect to the light bulb or to the
circuit breaker. For the spade type, take a couple of spades and solder
insulated wire to the spades.
The secret is to use something to use limit the current to less that the
original fuse, ie. if the circuit that has the problem has a 10A fuse, limit
the current to 5A. How? Use ohms and Watts law,
Ohms law: E = I * R E - Voltage, I - Current, R - Resistance.
Watts law: P = I * E P - power (watts)
So for a 10 A circuit in a 12 V system, R = E / I, you'll need
R = 12V / 10A = about 1 ohm of resistance.
You also need to account for the power: P = I * E or
P = 10A * 12V or 120 W.
This is why you use light bulbs. But they should be closely matched to the
power used by the circuit being worked on.
If you go too low of wattage, the light bulb will burn out, If you go to high,
then the light bulb won't limit the current enough to protect the circuit.
>This is a really great idea I never hear of, so thanks for sharing!
Yes, I use it for electronics. But you need incandescent bulbs.
https://www.instructables.com/Light-Bulb-Current-Limiter/
For automotive I prefer to have different size circuit breakers, 1, 5, 10, 20,
30A breakers and clip leads.
JohnT,
John T. Blair WA4OHZ email: jblair1948@cox.net
Va. Beach, Va Phone: (757) 495-8229
65 Morgan 4/4 Series V (B1106) 75 Bricklin SV1 (#0887) 48 TR1800 48 #4
Midget
65 & 77 Spitfire 71 Saab Sonett III 65 Rambler Classic 65 Volvo P1800
Morgan: http://autox.team.net/morgan/
Bricklin: http://www.bricklin.org/
If you can read this - Thank a teacher!
If you are reading it in English - Thank a Vet!!
>From Dennis Prager - The American Trilogy:
e pluribus Unum, "from many, one."
In God We Trust
Liberty - the power of choosing, thinking, and acting for
oneself; freedom from control or restriction
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On 01/12/2024 6:21 AM EST Moose wrote:
</div>
<div class="default-style">
</div>
<div class="default-style">
><span style="font-family: sans-serif; font-size: small;">This is
brilliant (figuratively AND literally) 8>)</span> <span
style="font-family: sans-serif; font-size: small;">But is this safe?
Couldn't it melt wires if there </span>
</div>
<div class="default-style">
<span style="font-family: sans-serif; font-size: small;">>is a
short?</span>
</div>
<div class="default-style">
</div>
<div class="default-style">
</div>
<div class="default-style">
Moose,
</div>
<div class="default-style">
</div>
<div class="default-style">
Yes it's safe if you do it correctly. You want to use a good socket,
if it's not plastic wrap it with electrical tape. We use this for finding
a short in a piece of electronic equipment. Put a 60W light bulb in a box
in series with the outlet that you plug the equipment into. This will
limit the current to 1/2 amp.
</div>
<div class="default-style">
</div>
<div class="default-style">
I also suggest (someone else mentioned this) that you make some sort of
adapter to plug into the fuse socket. For the old
</div>
<div class="default-style">
glass cylindrical fuses, solder a piece of insulated wire on each end so you
can connect clip leads to the wire to connect to the light bulb or to the
circuit breaker. For the spade type, take a couple of spades and solder
insulated wire to the spades.
</div>
<div class="default-style">
</div>
<div class="default-style">
The secret is to use something to use limit the current to less that the
original fuse, ie. if the circuit that has the problem has a 10A fuse, limit
the current to 5A. How? Use ohms and Watts law,
</div>
<div class="default-style">
</div>
<div class="default-style">
Ohms law: E = I * R E - Voltage, I -
Current, R - Resistance.
</div>
<div class="default-style">
</div>
<div class="default-style">
Watts law: P = I * E P - power (watts)
</div>
<div class="default-style">
</div>
<div class="default-style">
So for a 10 A circuit in a 12 V system, R = E / I, you'll need
</div>
<div class="default-style">
R = 12V / 10A = about 1 ohm of resistance.
</div>
<div class="default-style">
</div>
<div class="default-style">
You also need to account for the power: P = I * E or
</div>
<div class="default-style">
P = 10A * 12V or 120 W.
</div>
<div class="default-style">
</div>
<div class="default-style">
This is why you use light bulbs. But they should be closely matched to
the power used by the circuit being worked on.
</div>
<div class="default-style">
</div>
<div class="default-style">
If you go too low of wattage, the light bulb will burn out, If you go
to high, then the light bulb won't limit the current enough to protect the
circuit.
</div>
<div class="default-style">
</div>
<div class="default-style">
><span style="font-family: sans-serif; font-size: small;">This is a
really great idea I never hear of, so thanks for sharing!</span>
</div>
<div class="default-style">
</div>
<div class="default-style">
<br>
Yes, I use it for electronics. But you need incandescent bulbs.
</div>
<div class="default-style">
</div>
<div class="default-style">
<a
href="https://www.instructables.com/Light-Bulb-Current-Limiter/";>https://www.instructables.com/Light-Bulb-Current-Limiter/</a>
</div>
<div class="default-style">
</div>
<div class="default-style">
For automotive I prefer to have different size circuit breakers, 1, 5, 10,
20, 30A breakers and clip leads.
</div>
<div class="default-style">
</div>
<div class="io-ox-signature">
<p class="default-style">JohnT,<br><br><span style="font-family: tahoma,
arial, helvetica, sans-serif;">John T. Blair
WA4OHZ email: jblair1948@cox.net</span></p>
<div class="default-style">
Va. Beach,
Va
Phone: (757) 495-8229
</div>
<div class="default-style">
</div>
<div class="default-style">
65 Morgan 4/4 Series V (B1106) 75 Bricklin SV1
(#0887) 48 TR1800 48 #4 Midget
</div>
<div class="default-style">
65 & 77 Spitfire 71 Saab Sonett III 65 Rambler
Classic 65 Volvo P1800
</div>
<div class="default-style">
</div>
<div class="default-style">
Morgan: <a
href="http://autox.team.net/morgan/";>http://autox.team.net/morgan/</a>
</div>
<div class="default-style">
Bricklin: <a
href="http://www.bricklin.org/";>http://www.bricklin.org</a>
</div>
<p>If you can read
this -
Thank a teacher! <br><span style="font-family: tahoma, arial, helvetica,
sans-serif;">If you are reading it in English - Thank a Vet!!</span></p>
<p><span style="font-family: tahoma, arial, helvetica, sans-serif;">From
Dennis Prager - The American Trilogy:</span> <br><span style="font-family:
tahoma, arial, helvetica, sans-serif;"> e pluribus
Unum, "from many, one."</span> <br><span style="font-family: tahoma, arial,
helvetica, sans-serif;"> In God We Trust</span>
<br><span style="font-family: tahoma, arial, helvetica,
sans-serif;"> Liberty - the power of
choosing, thinking, and acting for </span>
<br><span style="font-family: tahoma, arial, helvetica,
sans-serif;">
oneself; freedom from control or restriction
</span> <br><br><br></p>
</div>
</body>
</html>
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