# Looking to build a transient generator

Discussion in 'Electronic Basics' started by [email protected], Sep 30, 2008.

1. ### Guest

A product I am designing requires a series of lab tests to judge
robustness against electrical transients.

One such test is to charge up a 100mH inductor in series with a 4 ohm
load (4ohm load to ground). Then, once the inductor is fully charged,
open the supply current to it from the high side. The resulting field
collapse will produce a substantial negative going voltage spike.

The circuit goes V+ to switch to inductor to resistor to ground.

The DUT is placed in parallel with the inductor/resistor series
combination, at the open end of the circuit once the switch is opened.

My question: I want to prolong the duration of the pulse by a factor
of 10x to create a more destructive burst of energy.

E=.5*L*I^2

I want to keep DC current through the branch the same. With that
said, one would reason I would need to bump up my inductance by a
factor of 10. This would require a 1H inductor!

Is it practical to find such a large inductance? Any ideas?

Thank you

Gerb

2. ### Phil AllisonGuest

** All depends on what DC current you are testing at.

Why not tell us ?

...... Phil

3. ### neon

1,325
0
Oct 21, 2006
go to the junk yard and get a car coil about 80mw power. that will not kill you but will surely get you mad.

4. ### Guest

You know Phil, no matter how hard I try, I always end up leaving out
some vital detail. Thanks for helping me out .

I would like to pass 3.2A +/- 200mA through the inductor. I realize
that as the inductor gains in size, so will its series DC resistance.
Therefore, at one point I might need to adjust my series resistance to
keep the branch current where I want it. This will result in a very
large inductor. Digikey does not carry these .

Gerb

5. ### Phil AllisonGuest

<
"Phil Allison"
You know Phil, no matter how hard I try, I always end up leaving out
some vital detail. Thanks for helping me out .

I would like to pass 3.2A +/- 200mA through the inductor. I realize
that as the inductor gains in size, so will its series DC resistance.
Therefore, at one point I might need to adjust my series resistance to
keep the branch current where I want it. This will result in a very
large inductor. Digikey does not carry these .

** Hmmmm -

a 3.5 amp rated inductor of say 1 Henry would weigh more than I care to
lift.

...... Phil

6. ### Guest

I understand its not going to be small nor light wieght. However, I
need to come up with something in close proximity to what I require.
Ideas anyone?

Gerb

7. ### Phil AllisonGuest

"Tim Wescott"
** Hammond have inductors for high voltage PSUs of up to 10H - but none
come anywhere near the OP's 3.5 amp requirement.

** Nonsense.

Transformer primaries are NOT efficient inductors and will SATURATE long
before 3.5 amps is reached.

** Need to start with a tranny of several kW rating and the lams have to be
re-stacked to create an appropriate air gap.

Big job.

...... Phil

8. ### Phil AllisonGuest

"Tim Wescott Fuckwit "

** **** you - you pathetic asshole.

** **** you - you pathetic asshole.

** **** you - you pathetic asshole.

The OP has not got access to every tranny in the WHOLE world.

FUCKWIT !!!!

** **** you - you pathetic ASD fucked asshole.

** **** you - you pathetic ASD fucked asshole.

** **** you - you pathetic ASD fucked asshole.

** The OP, like many who post here, did NOT need his idiotic Q answering in
the LITERAL way ASD fucked morons like YOU always do.

He needs to think of another way to do his test.

While YOU need to get a brain transplant - even a chimp's brain would be
an improvement.

...... Phil

9. ### Guest

I want to create a -400V transient (switching the inductor high side)
with a time contant of approximately 10mS. I have the option of
taking this to a local EMC lab that has the capability of generating
this pulse. However, I might want to run a few hundred products
through this test. EMC lab time is expensive. For reasons I would
rather not go into, I'd like to do this "on the cheap side". Thus,
building my own equipment from scratch and surplus bits.

I found two companies willing to construct inductors for me. The
problem, the cheaper of the two wanted \$2500USD. I currently don't
have that type of budget. I assume the solution you mentioed above
(High voltage supply and controller) will cost even more.

Thank you,

Gerb

10. ### Guest

I've looked into what the equipment I would need to do this would
cost. It is just not feasible.

11. ### Phil AllisonGuest

"Tim Wescott PIG ARROGANT Fuckwit "

** What a fucking ARSEWIPE you are - Wescuntt.

** What is sometimes the case is not THIS time !

All you ever SPEW is irrelevant & IRRATIONAL SHIT !!

** Spoken like a completely narcissistic FOOL.

All you are Wescuntt is a CLUELESS TWAT

dishing out 100 % STUPID advice.

YOU need to get a brain transplant - even a DEAD chimp's brain would be
an improvement.

Piss off - TURD BRAIN !!!

....... Phil

12. ### Guest

Dooohhhh! Interesting...

Gerb

13. ### Guest

Gentlemen. May I ask why this thread has turned into nothing but one
big pissing match? It seems you don't have much respect for each
other. That is OK. But please take the arguement elsewhere.

Thank you,

Gerb

14. ### Guest

Thank you. Now this is more inside my budget .

Gerb