NE-45 Lamp Resistance
Dave.H
know the value of the internal resistor (assuming of course it has
one, since it's rated for 105/125 volts) so I can add a suitable
external resistor to add up to 270k for 240 volt use.
Also a question about the socket I'd like to use, it hasn't got any
voltage rating, cat. # P8162 at www.dse.com.au
Whats the major differences between the NE-45 and NE-51, besides the
different base cap? Which one is the brighter one?
Dave.H
I'm also interested in building a relaxation oscillator with two NE-2
lamps, running on 240 volt AC. What would I need for this?
Richard Seriani
"Dave.H" <the1...@googlemail.com> wrote in message
news:78e16893-9b9a-4b51...@s8g2000prg.googlegroups.com...
Dave,
Did you try Google?
Here is one hit that may help, there were many others:
http://www.lamptech.co.uk/Spec%20Sheets/GE%20NE45.htm
Richard
Dave.H
> "Dave.H" <the19...@googlemail.com> wrote in message
Yeah, I found that right after I posted the first message.
Dave.H
So this NE-45 lamp only requires about 82k resistance for 240 volts?
John Fields
---
Everything you could ever want to know about neon glow lamps:
http://www.pmillett.com/tubedata/Glowlamp.pdf
It's about 81 megabytes long...
--
JF
Dave.H
What contact is the internal resistor tied to, the side contact or the
bottom contact? Also not too sure if 82k is right for 240 volt
operation.
John Fields
---
What difference does it make?
---
>Also not too sure if 82k is right for 240 volt
>operation.
---
On what do you base your indecision?
--
JF
Peter Bennett
<the1...@googlemail.com> wrote:
Doesn't matter which side the internal resistor is on (unless you are
doing something strange with the bulb, in which case you will have to
determine that experimentally).
The data sheet says to use an 82K for 240 volts, so it seems that that
is an appropriate value. However, if the lamp really draws 2 mA, 82 K
will drop 164 volts, which seems a bit much to me, so I might reduce
the resistor to 68K or so (to drop around 120V) if I needed a bit more
light.
--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
Dave.H
require a 270k resistor for 240 volt operation, I thought all neon
indicators did. Guess you learn something new each day. The reason I
wanted to know what contact the internal resistor is connected to is
so I can put it in series with an external resistor.
John Fields
<the1...@googlemail.com> wrote:
>On Jan 6, 12:50 pm, John Fields <jfie...@austininstruments.com> wrote:
>> On Sat, 5 Jan 2008 16:54:53 -0800 (PST), "Dave.H"
>> >What contact is the internal resistor tied to, the side contact or the
>> >bottom contact?
>>
>> ---
>> What difference does it make?
>> ---
>>
>> >Also not too sure if 82k is right for 240 volt
>> >operation.
>>
>> ---
>> On what do you base your indecision?
>>
>> --
>> JF
>The only neons I've ever dealt with before are the common NE-2 which
>require a 270k resistor for 240 volt operation, I thought all neon
>indicators did.
---
Since the NE-2 and the NE-45 both have maintaining voltages of about
55V, then the series resistance can be determined from the source
voltage and the rated lamp current.
For instance, an NE-2 has a rated current of about 0.5mA, so with a
240VRMS source the resistor must drop the difference between the
source voltage and the lamp's maintaining voltage with the rated
current going through the lamp:
Vs - Vm 240V - 55V
R = --------- = ------------ = 3.7E5 ohms = 370k ohms.
Il 5E-4A
Using 270k will result in an RMS current of 685µA through the lamp,
which will cause a brighter glow, but will decrease the life of the
lamp somewhat.
An NE-45 is rated for 2mA at 120VRMS, so its internal resistor must
be:
Vs - Vm 120V - 55V
R = --------- = ------------ = 3.25E4 ohms = 32.5k ohms.
Il 2E-3A
With a 240V source the total resistance needed would be:
240V - 55V
R = ------------ = 9.25E4 ohms = 92.5k ohms,
2E-3A
so the external resistor would be the difference between the two:
Rext = Rt - Rint = 92.5k ohms - 32.5k ohms = 60k ohms
The closest standard 5% value is 62k which would be fine and would
extend the life of the lamp.
It (the resistor) would dissipate:
P = I²R = 2E-3A² * 6.2E4R = 2.48E-1 watts ~ 0.25 watt,
so you should use a 62kohm +/- 5%, 1/2 watt resistor.
---
>Guess you learn something new each day.
---
:-)
---
>The reason I
>wanted to know what contact the internal resistor is connected to is
>so I can put it in series with an external resistor.
---
Since the internal resistor is already in series with the lamp,
connecting an external resistor in series with either the bottom
contact or the side contact will put it in series with the
lamp - internal resistor circuit: View in Courier:
. BOTTOM CONTACT
. /
.VIN>---[REXT]--->>---[RINT]---+
. |
. [LAMP]
. |
.VIN>------------>>------------+
. \
. SIDE CONTACT
.
.
. BOTTOM CONTACT
. /
.VIN>------------>>---[RINT]---+
. |
. [LAMP]
. |
.VIN>---[REXT]--->>------------+
. \
. SIDE CONTACT
.
. BOTTOM CONTACT
. /
.VIN>---[REXT]--->>------------+
. |
. [LAMP]
. |
.VIN>------------>>---[RINT]---+
. \
. SIDE CONTACT
.
.
. BOTTOM CONTACT
. /
.VIN>------------>>------------+
. |
. [LAMP]
. |
.VIN>---[REXT]--->>---[RINT]---+
. \
. SIDE CONTACT
--
JF
Dave.H
Thanks for that information. Got to swap out the old resistors for my
NE-2 lamps with higher rated ones.