/diy/ - Do It Yourself

>>1324219
>was testing with low frequency signals probably 100kHz LO 1Vpp and 1 or 10kHz test signal 2Vpp, whatever the case impedance wasn't really a problem.
It wouldn't work with voltages like that, you need like p-p 1V (feeding through a series resister) as a LO so it commutates the diodes and your test signal must be lower than that (so test signal doesn't commutate the diodes), like 100mV.

>>1324219
You wound the transformer wrong.
1st, changing winding direction from CW to CCW effectively changes "start" and "end" leads.
2nd, you should wind it trifial (either twist three wires together or just wound using three wires in parallel).
3rd, it looks like for 100kHz you have too low magnetizing inductance (use thinner wires and put more turns).

>>1322737
>being limited to 4 lug wheels only

Huh?

>>1322979

https://www.digikey.de/product-detail/en/allegro-microsystems-llc/A1104EUA-T/A1104EUA-T-ND/1005917

>>1320044
http://filehorst.de/d/cwFBCHhk

>>1318552

>>1318372

>>1307949
>illegal if your in the us
I believe it's illegal in most developed countries (surely there should be some limit on radiated power, like few mw's)

Anyways FM transmitters are available on ebay.

How much are willing to spend?

One of the easiest way is to rework a laptop AC adapter: there is reference divider for setting output voltage somewhere near lm358/dap08/or whatever is used, you need to change resistor(s) values to set 15 volts or so. All laptop adapters (except chinese shit) do have current limiting circuitry. The only missing things for a charger are reverse polarity protection (you either should be careful and always connect it right or use ~5A fuse) and alligator clips.

I mod two adapters that way, one is in my garage charging a battery that I use to power car audio amp.

>>1306835
>What would be some good values to start with for that diagram?

There is numerous IGBT's designed specifically to drive ignition coils (some are smart enough to have over-current protection). I'd suggest you to switch to 350-400V devices and/or copy ignition drivers found in VEMS/microsquirt/megasquirt/rusEFI/etc.

BTW why don't you go with COP's with builtin drivers? For example you can get COP's from yaris for cheap and they are quite successfully used on 2JZ.

>>1306819
>Is this going to murder my FET?

Nope if you are within absolute maximum rating of "Ear" or "repetitive avalanche energy" for your MOSFET. Basically your ignition circuit is 1-to-1 copy if UIS test circuit.

>>1306822
>i'm of the opinion that the 100v cap there is just a great coincidence.

Body diode in MOSFET's is actually a zener, for a 100V mosfet it's a 100V zener, for 200V MOSFET it's a 200V zener. And it's not a limp one, it can dissipate about the same amount of power as a mosfet can. Again, check data sheet. Maximum avalanche current for IRF520 is 9.2A.

>>1306831
>If my FET was going to release the blue ghost, how fast would that happen? Would it take 1 pulse or 10 or 10,000? I've left it running at like 5 Hz for the last 2 or 3 hours and it's still going.

It's safe. Basically if the FET isn't too hot and avalanche current is less than 9A you are good to go.

>>1306831
>Why does a 20 volt Zener between the drain and ground kill the spark?
You are clamping voltage across primary winding and since primary and secondary windings on igntion coils are magnetically coupled you clamp output voltage as well.

>>1306831
>Why does doing the same thing with a 1N4001 do nothing at all?
It's not a 50v Zener, it is designed to withstand at least 50v or whatever number but there is no guarantee it will break down at that voltage.

You can test break down voltage safely: you need high voltage source and like 1-10 Megohm resistor in series. Then you rise HV until you register 1-5-100uA (or whatever number the datasheet specifies).

>>1305708
You can also partially test the SMPS in safe manner using these techniques.

1. Supply 20-50V across bulk caps, rig some pulse generator to trigger power transistor with like 30-80 kHz & 0.1-0.5 Duty. You will be able to probe most parts of the SMPS with a scope and multimeter and check a lot. Ideally you want to control duty cycle & frequency (and amplitude of course). You may want to disconnect PWM IC or a driver (in this very case and the schematic you posted it's not needed).

2. Build yourself a half-bridge using IR2153 or similar device (you need ca. 0.5 duty and variable frequency), supply HB FET's with a lab power supply so you can vary signal level. Then connect HB output directly to the transformer (primary and/or secondary). Voilà, you can check rectifiers and often feedback and also check transformer.

Most likely air-core you use has strong enough stray H-field to induce enough voltage on source/drain lines to turn on FET's.

To fix that you need to reduce dI/dt and reduce high/current & high dI/dt loop areas.

To learn what's going on you may want to build yourself few H & E probes.

>>1305526
PS_ON# is active low, you connect it to ground to activate the PSU.

On Xbox PSU you connect PS_ON to +5VSB to enable it, right?

Thus PS_ON# signal going from motherboard to Xbox PSU must be inverted.

Basically you need to connect +5VSB from XBox PSU to your PC +5VSB
And a PMOS or a PNP BJT to invert PS_ON# and supply PS_ON for Xbox PSU.

>>1305316
That small transistor in the feed back loop (the one on the right, BTW if you'd use reference designators like R1/R2/R3, Q1,Q2, etc it would be much easier to refer to them) must be checked or replaced.

>>1305492

>Frustrating
>I replaced the faulty optowith one i had laying around. Still NFG... i checked everything on the primary side, nothing wrong...

Post schematic of the primary side, write down component values and mark the ones that you replaced.

If you are desperate and have no idea what to do you may start with brute force approach: start replacing everything (start from semiconductors like IC's, then transistors, resistors and caps). It's not the most cost efficient or the fastest way to fix things but it works.

Check ceramic caps, common failure mode is short circuit. Check resistors, "low" ohm resistors could burn or crack and become "high" ohm ones.

>>1305269
>>1305288

Your trolling attempts are lame and naive. All you managed to do is shit in few threads with off topic and that's it. Pathetic :)

>>1305251
Some if not all are isolated but you must not rely on that, as it may be safe for the scope but not safe for you (accidents happen). If your scope is grounded then connecting scope's ground to PSU primary ground (bulk caps gnd) will strike quite an arc and you'll destroy the probe and may damage the scope.

>>1305228
>I would rather not blow my dick off, do i follow his advice or not ?

It's safe to connect a probe to a 1.5v battery. You absolutely can't damage the scope that way. Using 10:1 probes requires calibration, you should have a square wave output on the scope for that.

However you shouldn't try to poke the PSU with the scope unless you:

1) run the PSU with galvanic isolation from the mains;

2) measuring high-voltage stuff requires 100:1 probes and you have to understand you probe rating / frequency-dependent derating (for example your 100:1 probe is designed to work with 1000V RMS max, but if frequency is like 1 or 10 MHz than RMS voltage rating may be mere 200V).

2) run PSU disconnected from the mains (it's often possible to run PWM IC with a lab PSU & then exercise feedback loop by providing fake output voltage, for example). Sometimes it's possible to run the PSU with very low input voltage, like 50-80V, it makes probing easier.

That being said, don't rush to poke the PSU with the scope.

Draw its schematic first, you need to understand how it works (including feedback & start up circuits).

>>1305220
You must either have reading comprehension issues or mentally challenged if you think I have something to do with another person who is replying and talking to himself.

>>1305191
Oh and don't forget about opto-couplers. They also go bad (either LED's or photo-transistor can go bad, sometimes LED loses emission and current transfer ratio becomes extremely low).

>>1305186
>I have one but i've never used it and i dont know how it works.
>I do understand how these work but it's the first one i'm repairing that has a 'real' problem.

What kind of scope and probes do you have?

Check all diode for short, including small-signal ones (1n4148 and alike), zeners for short. Check that IC's don't have short between VCC and GND pins. Check transistor E-B / B-C junctions for shorts. It's a common failure mode for semiconductor devices (going open isn't that common but may also happen).

Check primary winding for continuity.

If it's flyback with current mode control check current sense resistor (it's a "big" resistor in Emmiter-GND or Source-GND path).

Once all that is checked you should find the oscillator (it could be integrated to a PWM chip or you may have self-oscillating PSU, google "ringing choke conerter" for info), check if it starts or not (if it doesn't you have to fix it).

If there is a PWM IC you should check it's start up circuit. There could be something like a "high" value resistor from 310VDC bus to PWM IC Vcc pin.

Be careful while testing the PSU. While working with "high" voltage you should have someone in nearby.

Good luck.

>>1305152
Well it's autism at its finest. Flooding, spamming and generally acting plain weird.

I've seen few autists (two, to be precise) in real life. Poor people. Without internet (and computers) they would likely loose a major way of communication with society and loose their social skills fast. You gotta be patient...

>>1305144
Do you have an oscilloscope?

Do you have basic knowledge on SMPS? E.g. understand how flyback, forward converters work?