All 4 Rail Fuses go Nucular
- Thread starter FredR
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Really gotta watch that gain a little more closely. Eight
amp rail fuses zapped.
No damage to 9Kappa woofers. Not so sure about ears.
View attachment 31528
amp rail fuses zapped.
No damage to 9Kappa woofers. Not so sure about ears.
View attachment 31528
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Ron,
SOA stands for "Safe Operating Area".
Wikipedia has this definition:
https://en.wikipedia.org/wiki/Safe_operating_area
Additionally:
Bob Carver's patent (US patent 3,727, 148) talks about his "energy limiting" protection circuit. This circuit allowed the output transistors to absorb more power, for short periods in the range of safe operation. "The utilization of the energy limiting circuit allows the number of output transistors to be reduced by as much as much as two-thirds....."
https://worldwide.espacenet.com/pub...T=D&ND=3&date=19730410&DB=EPODOC&locale=en_EP
Ed
SOA stands for "Safe Operating Area".
Wikipedia has this definition:
https://en.wikipedia.org/wiki/Safe_operating_area
Additionally:
Bob Carver's patent (US patent 3,727, 148) talks about his "energy limiting" protection circuit. This circuit allowed the output transistors to absorb more power, for short periods in the range of safe operation. "The utilization of the energy limiting circuit allows the number of output transistors to be reduced by as much as much as two-thirds....."
https://worldwide.espacenet.com/pub...T=D&ND=3&date=19730410&DB=EPODOC&locale=en_EP
Ed
Last edited:
"There are two limitations on the power handling ability of a transistor; average junction temperature and secondary breakdown. Safe operating area curves indicate IC – VCE limits of the transistor that must be observed for reliable operation; i.e., the transistor must not be subjected to greater dissipation than the curves indicate."
The data sheets for early transistors like the XPL909 (GM/Delco DTS411) and FPL909 (Fairchild FT411’s) did not contain S.O.A. specs or Ic-Vce plots. Many of the manufacturers made similar parts utilizing their own prefixes (i.e. Delco DTS411, Fairchild FT411, Motorola MJ411 and RCA411). Also, when testing transistors the pulse widths and duty cycles has not been consistent from manufacturer to manufacturer over the years. My best guess at this time is that the S.O.A. at 80V for these earlier transistors was a little less than 1 Adc.
“Second Breakdown Collector Current with Base Forward Biased”
MJ15024:
(Vce = 80Vdc, t=0.5s (non-repetitive): 2 Adc
MJ21194:
(Vce = 80Vdc, t=1s (non-repetitive): 2.5 Adc
MJ21196:
(Vce = 80Vdc, t=1s (non-repetitive): 2.5 Adc
http://www.onsemi.com/pub/Collateral/MJ21195-D.PDF (Also contains specs for MJ21196)
It is interesting to note that the MJ21194’s and MJ21196’s are “Total Harmonic Distortion Characterized”
Total Harmonic Distortion at the Output VRMS = 28.3 V, f = 1 kHz, PLOAD = 100 WRMS
hFE unmatched: THD 0.8%
(Matched pair hFE = 50 @ 5 A/5 V) hFE matched: THD 0.08%
See Figure 17 “Total Harmonic Distortion Test Circuit” in MJ21195/MJ21196 data sheet.
NOTE: I don’t see a value for the capacitor in the circuit. Perhaps Joe may have some ideas on what value to use.
Ed
The data sheets for early transistors like the XPL909 (GM/Delco DTS411) and FPL909 (Fairchild FT411’s) did not contain S.O.A. specs or Ic-Vce plots. Many of the manufacturers made similar parts utilizing their own prefixes (i.e. Delco DTS411, Fairchild FT411, Motorola MJ411 and RCA411). Also, when testing transistors the pulse widths and duty cycles has not been consistent from manufacturer to manufacturer over the years. My best guess at this time is that the S.O.A. at 80V for these earlier transistors was a little less than 1 Adc.
“Second Breakdown Collector Current with Base Forward Biased”
MJ15024:
(Vce = 80Vdc, t=0.5s (non-repetitive): 2 Adc
MJ21194:
(Vce = 80Vdc, t=1s (non-repetitive): 2.5 Adc
MJ21196:
(Vce = 80Vdc, t=1s (non-repetitive): 2.5 Adc
http://www.onsemi.com/pub/Collateral/MJ21195-D.PDF (Also contains specs for MJ21196)
It is interesting to note that the MJ21194’s and MJ21196’s are “Total Harmonic Distortion Characterized”
Total Harmonic Distortion at the Output VRMS = 28.3 V, f = 1 kHz, PLOAD = 100 WRMS
hFE unmatched: THD 0.8%
(Matched pair hFE = 50 @ 5 A/5 V) hFE matched: THD 0.08%
See Figure 17 “Total Harmonic Distortion Test Circuit” in MJ21195/MJ21196 data sheet.
NOTE: I don’t see a value for the capacitor in the circuit. Perhaps Joe may have some ideas on what value to use.
Ed
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