SA-9800 Frys Speakers!
- Thread starter ehc68
- Start date
ehc68 said:
Yes, it is the 'keys to the kingdom"
Depending upon the actual transistor die, it will start to turn on around 0.6 volts and then after that a small change in voltage (and base current) will cause a larger change in the collector to emitter current.
That's when all those graphs in the transistor's data sheet start to come into play...
Gain of the transistor is a ratio of the collector to emitter current versus the base to emitter current. Of course the total emitter current is a total of the base and collector currents.
http://www.bcae1.com/trnsistr.htm is an informative web page...
after you are done with that page, the stuff below will make a great deal of sense....
2x 2sd667 (Q1,Q2) 120v, 1 amp, 0.9 watt 140mhz npn transistor with ECB layout
2x 2sd756 (Q7,Q9) 120v, 0.05 amp, 0.75 watt 350mhz npn transistor with ECB layout
1x 2sb716 (Q3,Q4,Q8,Q10) 120v, 0.05 amp, 0.75 watt 150mhz PNP transistor with ECB layout
volts is maximum volts collector to emitter (when turned off)
amps is maximum collector current (when turned all the way on)
watts is maximum heat dissapation (collector current x volts across collector to emitter)
mhz is the (maximum) speed at which the transistor's gain is one....
gain I didn't list, power transistors (higher collector currents) generally have lower gains...
BY THE WAY, I don't know WHY they selected the NTE 459....
The NTE 459 is OBSOLETE at MOUSER, while the NTE 458 IS in stock, a more appropriate match and is $2.00 each.... even the pinouts are the same as the sk34... just a slightly higher power dissapation... (k34=50v, 0.150w) vs (458=50v, 0.250w)
If I wasn't waiting for some close matches (512-ksk30yta, 50v 0.100w) to come in at the end of the next month at $0.06 each I would be tempted...
The NTE 459 is OBSOLETE at MOUSER, while the NTE 458 IS in stock, a more appropriate match and is $2.00 each.... even the pinouts are the same as the sk34... just a slightly higher power dissapation... (k34=50v, 0.150w) vs (458=50v, 0.250w)
If I wasn't waiting for some close matches (512-ksk30yta, 50v 0.100w) to come in at the end of the next month at $0.06 each I would be tempted...
ehc68
My SX-1050
This is off the subject and I promise this will be the ONLY unrelated question I ask.
Do you know what would be a good replacement for an OLD .047mfd 400V wax/paper cap? I looked up caps of this value and found that there are TONS of different types, and I have no clue which one I need. It came off of an old V-M phonograph.
Do you know what would be a good replacement for an OLD .047mfd 400V wax/paper cap? I looked up caps of this value and found that there are TONS of different types, and I have no clue which one I need. It came off of an old V-M phonograph.
ehc68 said:
mouser.com 75-225P400V0.047 Vishay Sprague Polyester Orange Drop Capacitors 400V .047 uF in stock at $0.99 ea
glen65 said:
Drat... GOOD POINT... If it's connected to the power line it needs to be a safety cap...
http://www.justradios.com/safetytips.html
discusses what you could have and what you would need, it's a bit of a read but it's worth it.
I have some 0.0047 uf XY and some 0.01 uF X safety capacitors.
BUT... 0.047 IS a large value for a safety cap...
ehc68 said:
If you were going to place an order with mouser, you could get one or two nte-458 jfets (just in case) part # 526-NTE458 at $2.00 each....
ehc68 said:
If you look at the availability column, which shows "ON-Order", or try to order them, you will find out that they have none now, are on order, and have a 6/27/2007 Estimated Ship Date.
Think of it as insurance against Murphy's Law....
If you don't have a spare... you will need one... if you have a spare, it will stay a spare...
If you don't have a spare... you will need one... if you have a spare, it will stay a spare...