Types of Capacitors in used in TV's

[Chris F.]

This may be slightly off-topic for this group, but I figured you guys
would most likely be able to help me. I'm working on building a Tesla coil,
and as anyone familiar with the hobby knows, capacitors are a vital part of
each unit. I'm particularly interested in building my own tank capacitor
from multiple HV polypropylene caps (known as a Multi-Mini-Cap), but I'm
having some trouble identifying the different types.
Electrolytic, ceramic, and even tantalum types are easy to identify. But
I'm having trouble figuring out how to distinguish the mylar types from the
polypropylene. Most of the caps I have are pulled from old 70's, 80's, and
some 90's color TVs. They come in a variety of colors, shapes, and sizes,
and values range from 0.47 / 100VDC - 0.068 / 1600 VDC. Since visual
inspection is no help, is there any test criteria I can use to correctly
sort the two types? BTW I do not have an ESR meter at this time, but I have
other equipment that may be helpful (function generators, etc).
Polypropylene types are far preferred for Tesla coiling, because of their
better ability to withstand high currents and frequencies. Even one mylar
cap mixed in with them could cause a problem, so I want to be absolutely
certain.
Any advice would be appreciated.

 

[Asimov]

"Chris F." bravely wrote to "All" (15 May 04 17:44:25)
--- on the heady topic of "Types of Capacitors in used in TV's"

CF> From: "Chris F." <[email protected]>

CF> This may be slightly off-topic for this group, but I figured you
CF> guys would most likely be able to help me. I'm working on building a
CF> Tesla coil, and as anyone familiar with the hobby knows, capacitors are
CF> a vital part of each unit. I'm particularly interested in building my
CF> own tank capacitor from multiple HV polypropylene caps (known as a
CF> Multi-Mini-Cap), but I'm having some trouble identifying the different
CF> types. Electrolytic, ceramic, and even tantalum types are easy to
CF> identify. But I'm having trouble figuring out how to distinguish the
CF> mylar types from the polypropylene. Most of the caps I have are pulled
CF> from old 70's, 80's, and some 90's color TVs. They come in a variety of
CF> colors, shapes, and sizes, and values range from 0.47 / 100VDC - 0.068
CF> / 1600 VDC. Since visual inspection is no help, is there any test
CF> criteria I can use to correctly sort the two types? BTW I do not have
CF> an ESR meter at this time, but I have other equipment that may be
CF> helpful (function generators, etc). Polypropylene types are far
CF> preferred for Tesla coiling, because of their better ability to
CF> withstand high currents and frequencies. Even one mylar cap mixed in
CF> with them could cause a problem, so I want to be absolutely certain.
CF> Any advice would be appreciated.

Tesla coils can generate from 100,000 volts and upwards of 10,000,000.
I really don't think a capacitor scavenged from a broken tv is
suitable. The usual DIY techniques seem to involve 1/4 inch glass
plates with sheets of aluminium flashing in buckets of oil and people
who write the FAQ's seem to make a big deal out of air bubbles.

Maybe you are building a model of a Tesla coil?

Asimov
******

.... This message transmitted on 100% recycled photons.

 

[Chris F.]

Tesla coils can generate from 100,000 volts and upwards of 10,000,000.
I really don't think a capacitor scavenged from a broken tv is
suitable. The usual DIY techniques seem to involve 1/4 inch glass

-snip-

Surely you don't think I'd use a single capacitor from an old TV as my
tank cap on a Tesla coil. I intended to use an arrangement of
series/parallel strings of caps, to get the required value and voltage. The
tank cap usually has to form a value of around 0.01 uF @ 20 - 30 kVDC. It
could take several hundred caps to achieve this value, which isn't a problem
because I have bucketfulls of these laying around.
Right now I just want to know how I can identify the polypropylene caps
from the mylar ones.

 

[Asimov]

"Chris F." bravely wrote to "All" (16 May 04 13:44:11)
--- on the heady topic of "Re: Types of Capacitors in used in TV's"

CF> Surely you don't think I'd use a single capacitor from an old TV as
CF> my tank cap on a Tesla coil. I intended to use an arrangement of
CF> series/parallel strings of caps, to get the required value and
CF> voltage. The tank cap usually has to form a value of around 0.01 uF @
CF> 20 - 30 kVDC. It could take several hundred caps to achieve this value,
CF> which isn't a problem because I have bucketfulls of these laying
CF> around.

The thought of having to make many hundreds of solder joints that are
100% reliable seems quite daunting. I remember wiring a 6x6 stereo
crosspoint switch box once and it was to put it mildly tedious let
alone having to cut all the jumper wires to length. Damn, I really
should have made a pcb that time!


CF> Right now I just want to know how I can identify the
CF> polypropylene caps from the mylar ones.

The maker's name and series number should definitely identify it but
here is a table that has some general id codes:
(BTW mylar/polyester caps are not the best around.)


Tolerance

Code / Colour / tolerance
A +20% / -10% (used on electrolytics)
C Red +/- 0.25pF (caps <= 10pF)
D Green +/- 0.5pF (caps <= 10pF)
E Brown +/- 1.0pF (caps <= 10pF)
F Red +/- 1% (caps > 10pF)
G Green +/- 2% (caps > 10pF)
J Brown +/- 5% (caps > 10pF)
K White +/- 10%
L +/- 15%
M Black +/- 20%
N +/- 30%
P +100% / -0%
Q +30% / -10% (used on electrolytics)
S +50% / -20%
W +50% / -10%
W +40% / -20% (used on electrolytics)
Z Grey +80% / -20%

Temperature Characteristics

Tempco EIA JIS Colour Tempco
code PPM/degree C

P100 R/V +100
NP0 C0G C Black 0
N30 S1G H -30
N033 S1G Brown -33
N075 U1G Red -75
N080 U1G L Red -80
N150 P2G P Orange -150
N220 R2G R Yellow -220
N330 S2H S Green -330
N750 U2J U Violet -750
N1500 P3K W Or/Or -1500
N2200 R3L -2000
P350/N1000 SL SL +350 TO -1000

JIS caps sometimes append a tempco tolerance

G +/- 30 PPM/deg C
H +/- 60 PPM/deg C
J +/- 120 PPM/deg C
K +/- 250 PPM/deg C
L +/- 500 PPM/deg C

Alternatively

1st char min Temp
X -55
Y -30
Z +10

2nd Char
5 +85
7 +125

3rd char Stability
F +/- 7.5%
P +/- 10%
R +/- 15%
S +/- 22%
T +22 / -33 %
U +22 / -56 %
V +22 / -82 %

Film Capacitors

KP Polypropylene film / foil
KS Polystyrene film / foil
KT Polyester film / foil
MK Metalised plastic film
MKP Metalised Polypropylene
MKT Metalised Polyester
MKT-P Metalised Polyester /paper
MKY Metalised low loss Polypropylene
MKL (MKU) Metalised Cellulose Acetate


Copied from the data section of a DSE catalogue (WWW.DSE.COM.AU)


Asimov
******

.... Batteries not included.

 

[Wayne Tiffany]

I don't have an answer for you, but I would presume you have already gone
here to see the King of the Tesla.

http://www.laushaus.com/tesla

WT

 

[Chris F.]

Thanks for the advice, but looking through my caps I can find very few
such markings. The only markings I can find, other than the
capacitance/voltage values, are the single-letter tolerance values. Many of
these seem to be generic types. A few of the branded ones include
Matsushita, Daewoo, and Sprague.
I guess I will just have to use them anyway and see what happens. If they
don't work out well I'll just have to shell out a few bucks for some decent
caps.