Crack voltage question

BillWay · 7312

0 Members and 1 Guest are viewing this topic.

Offline Dyna Saur

  • Full Member
  • ***
    • Posts: 75
  • Yippie-Ki-Yay....
Reply #15 on: May 07, 2010, 02:20:51 PM
IIRC, 430 (5%)  or 432 (1%)  ohms is pretty darn close, for 1.57V on the cathode.  At least that worked for the FPIII at one time.  The Crack's input circuit is  the same as for the FPIII.

I "cheated" a while ago and bought a batch of HLMP-6000s from Jameco.  Ditto for the transistor sets for the "source" and "sink" C4S circuits.

Now all I have to do is determine exactly in which (of many) box they are residing within, in my cellar...

Crack Progress report:  So far I got the wood base glued together. Been real busy cleaning out my Dad's house which is about 125 miles from here, still have a few more trips to make before that's done...

/ed B

ed brown


Offline nsorens

  • Jr. Member
  • **
    • Posts: 21
Reply #16 on: May 11, 2010, 09:12:30 AM
Put in the new LED and everything is checking out great.  Sounds great too.  Thanks Paul for the resistor idea. 
Question, if the resistor will work as a replacement, why use the LED?



Offline Grainger49

  • Hero Member
  • *****
    • Posts: 7175
Reply #17 on: May 11, 2010, 09:18:31 AM
The LED controls the current better than a resistor.  By that I mean that the voltage can change across the LED and the current stays the same.  A resistor, in contrast, passes a current that is always proportional to the voltage.



Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19319
Reply #18 on: May 11, 2010, 10:14:30 AM
A resistor would indeed work and be way, way less expensive than the LED (5 cents vs. well over 20 cents for the LED).  Of course, the LED sounds way, way better, and it is a very low impedance device. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man