Forum: General Electronics Technical Discussion
05-13-2022, 12:28 PM
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Replies: 39
Views: 945
Re: TIP120 Question
Back in the late 70s and into the 80s, transistors were used rather than Darlingtons. At Boschert, we used 2N654# and MJE1300# transistors (TO-204 and TO-220, respectively) from Motorola. That was...
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Forum: General Electronics Technical Discussion
05-13-2022, 12:06 PM
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Replies: 39
Views: 945
Re: TIP120 Question
In addition to limiting the realistic maximum switch frequency, during those turn-on and turn-off times, the device is in its linear reason, i.e. dissipating power. As those turn-on and turn-off...
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Forum: General Electronics Technical Discussion
05-12-2022, 11:44 AM
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Replies: 39
Views: 945
Re: TIP120 Question
redwire is correct that I was confusing a C-B resistor with a Baker Clamp, which uses a diode to reduce storage time. Lo siento.
Basically, transistors' rise, fall, and storage time combine to...
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Forum: Troubleshooting Power Supplies and Power Supply Design
05-08-2022, 06:16 PM
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Replies: 12
Views: 313
Re: Power Man ip-p300bn7-2 blown
Putting together anecdotal comments I’ve seen around here, I wonder if a lot of the snap-in type caps, which were originally designed for 50/60 Hz usage, are not suitable for the high frequency...
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Forum: General Electronics Technical Discussion
05-06-2022, 11:40 AM
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Replies: 39
Views: 945
Re: TIP120 Question
I sit partially corrected about the TIP120 incorporating B-E resistors. However I think those are to prevent leakage or noise from turning on the Darlington. IIRC, it's a C-B resistor that keeps a...
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Forum: General Capacitor Questions & Issues
05-06-2022, 11:28 AM
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Replies: 7
Views: 244
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Forum: General Capacitor Questions & Issues
05-05-2022, 06:20 PM
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Replies: 7
Views: 244
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Forum: General Capacitor Questions & Issues
05-04-2022, 04:40 PM
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Replies: 7
Views: 244
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Forum: General Capacitor Questions & Issues
05-04-2022, 04:22 PM
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Replies: 18
Views: 344
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Forum: General Capacitor Questions & Issues
05-02-2022, 11:17 AM
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Replies: 18
Views: 344
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Forum: General Capacitor Questions & Issues
05-02-2022, 11:13 AM
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Replies: 18
Views: 344
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Forum: General Electronics Technical Discussion
05-01-2022, 06:00 PM
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Replies: 12
Views: 312
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Forum: General Capacitor Questions & Issues
05-01-2022, 05:48 PM
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Replies: 18
Views: 344
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Forum: General Electronics Technical Discussion
04-29-2022, 10:58 AM
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Replies: 12
Views: 312
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Forum: General Electronics Technical Discussion
04-29-2022, 10:42 AM
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Replies: 6
Views: 234
Re: Resistor value - color coding
Based on the chart below, I'm guessing .3 ohm, 250 ppm tempco.
https://www.neodensmt.com/Content/upload/2019233559/201906241320349978362.jpg
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Forum: General Electronics Technical Discussion
04-27-2022, 10:56 AM
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Replies: 39
Views: 945
Re: TIP120 Question
I suggest adding a resistor base-emitter to reduce sensitivity to leakage and noise. This is normal practice with regular transistors, and I would think the high beta of a Darlington would make doing...
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Forum: Troubleshooting Power Supplies and Power Supply Design
04-25-2022, 11:34 AM
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Replies: 3,191
Views: 1,037,752
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Forum: Troubleshooting Power Supplies and Power Supply Design
04-22-2022, 11:50 AM
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Replies: 3,191
Views: 1,037,752
Re: Power supply build quality pictorial. part 2
How often have I posted this: those heatsinks do look reasonably substantial. The main transformer looks reasonable as well. 820uF for the input lytics seems a bit marginal for 500W (more OK for...
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Forum: Troubleshooting Power Supplies and Power Supply Design
04-14-2022, 03:37 PM
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Replies: 70
Views: 1,723
Re: A question about PWM IC's
Start-up current comes from "VIN" (also, line voltage sense). After it has started, house-keeping power for the IC comes from "VDD".
It is a current mode regulator, so it needs the output voltage...
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Forum: General Electronics Technical Discussion
04-11-2022, 05:45 PM
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Replies: 12
Views: 529
Re: Need new part for microwave
It's a bimetal thermal switch. It should open up if what it's mounted on gets too hot. It should close again when what it's mounted on cools.
On eBay,...
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Forum: General Electronics Technical Discussion
04-05-2022, 11:59 AM
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Replies: 13
Views: 642
Re: Question about MOSFET as a switch and a cap?
Assuming an N-channel MOSFET, for it to turn on the Gate must be several volts more positive than the source. The meaning of "several volts" will depend on the threshold voltage of the MOSFET....
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Forum: Troubleshooting Power Supplies and Power Supply Design
04-03-2022, 10:00 AM
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Replies: 14
Views: 520
Re: Aerocool cylon 700watt Atx psu
I think it's a Tiny Switch type all-in-on regulator. The "missing" pin 7 is probably the spacing between pin 8, the output MOSFET Drain, and pin 6, the Source. Whether it's literally is a Tiny Switch...
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Forum: Troubleshooting Power Supplies and Power Supply Design
03-27-2022, 06:17 PM
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Replies: 7
Views: 469
Re: Delta DPS400-MB, pwr_ok stays low
You may be able to find the pin-out and a schematic for that custom Delta ASIC. It was “DNA1002” when I was at Delta in the late 90s. Look to see if the PG output needs a pull-up resistor, and if...
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Forum: General Capacitor Questions & Issues
03-27-2022, 06:02 PM
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Replies: 1,015
Views: 515,883
Re: The Hall of Shame - Badcaps Photo Montage
The PL and PR series were discontinued long ago, casualties of RoHS. The reconstituted the PL series as the PM series, and due to customer demand brought back the PR series as the PS series. I know...
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