I NEED HELP 5V TO 10V PWM
- Thread starter Growmau5
- Start date
Yesdog
Well-Known Member
Yea, NPNs are CBE (top to bottom respectively on my layout, picture and schematic)
EDIT: shared ground at the emitters- guess this would be a 'common emitter' circuit, with an NPN inverter.
EDIT2: And the DIM circuit switches between 2 paths: highest resistance at the always-open parallel path (fixed resistor setting the 'max' voltage), and lowest resistance at the normally-closed NPN circuit.
Last edited:
Yesdog
Well-Known Member
fuck, did i just wire this up backwards? I hate that these simulators don't have actual transistor packages available.
Yesdog
Well-Known Member
Yesdog
Well-Known Member
CannaBruh
Well-Known Member
With the flat side facing you, leads pointing down, left to right:
Emitter, Base, Collector
Yesdog
Well-Known Member
hmm, so i flipped both transistors- still seeing the same results from the ohm-meter: guessing it still might be related to too low of current tho, or I guess the ohm meter can be a constant-voltage supply too (suppose the math works the same).
Going to get it wired up tho soon, see what happens....
Yesdog
Well-Known Member
Ugh... so its either A) the current supply on the ohm meter is too weak B) the ohm meter is constant voltage instead of constant current C) the resistance on the NPNs is far from what was modeled and im getting some serious bleed through the right-most NPN base.
EDIT: I wouldn't care about the ohm meter as much, except i modeled this with an ohm meter instead of the 0.1mA DIM circuit, and everything showed up as expected.
EDIT: I wouldn't care about the ohm meter as much, except i modeled this with an ohm meter instead of the 0.1mA DIM circuit, and everything showed up as expected.
VegasWinner
Well-Known Member
try using a 10uf cap to reduce bleed on one leg and a .1uf cap on the other leg to help isolate current.
VegasWinner
Well-Known Member
Put a cap on the collector leg of the first transistor, and the other on the emitter leg.
Yesdog
Well-Known Member
Hmm, still getting some weird discharge/charge spikes. I had to do 2 equivalent caps too, otherwise I was getting a low or high bias (i did remove the 100 ohm res from the DIM circuit tho).
EDIT: not like the spikes are going to do much for the end reading i don't think. I just don't understand capacitors and the spikiness worries me =\
EDIT: not like the spikes are going to do much for the end reading i don't think. I just don't understand capacitors and the spikiness worries me =\
Yesdog
Well-Known Member
Hmmm so am i asking for trouble here by getting caps involved? The frequency of the Pi PWM varies with the duty cycle- not sure what the ranges are, but frequency isn't totally reliable here.
VegasWinner
Well-Known Member
So true. You have to break a couple eggs to make an omelette. I have built a few circuits. The key is to use a cap to isolate your two grounds and reduce noise in the circuit.
VegasWinner
Well-Known Member
Pwm frequency is constant and current is constant voltage varies alone.
Yesdog
Well-Known Member
Fair enough. Well, once i find some decent solid core wire I'm just gonna man up and try the damn thing out lol
wietefras
Well-Known Member
@VegasWinner, Why would you want to reduce noise in the circuit? Why would that be an issue at all? Let alone talk about "reducing bleed". As if a cap is going to prevent that. If you want to do some filtering you need a combination of cap plus resistor. Still I fail to see how that's an issue here. We're not looking for precision voltages, but a simple PWM signal.
Seriously, with all the weird things you keep saying and not even understanding basics like high- vs low-side switched and then also your insistence that we need an extra 10V source, it really sounds like you are pretending to be more experienced than you actually are.
@Yesdog ,
I'd keep this as simple as possible.
The simple circuit with one transistor works fine. Two transistors would mean you don't need to invert the signal in the software and works fine also. All you need to add are some resistors.
Besides, there are plenty of example circuits that you can look up.
Seriously, with all the weird things you keep saying and not even understanding basics like high- vs low-side switched and then also your insistence that we need an extra 10V source, it really sounds like you are pretending to be more experienced than you actually are.
@Yesdog ,
I'd keep this as simple as possible.
The simple circuit with one transistor works fine. Two transistors would mean you don't need to invert the signal in the software and works fine also. All you need to add are some resistors.
Besides, there are plenty of example circuits that you can look up.
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