From a conceptual perspective, very low quiescent current (aka idle/standby current) when unactivated is entirely achievable. What your design will need to do is assess how much each component will draw at idle, and if it’s too high, then you may need to have gates which turn off those high-draw components when idling.
From a cursory Google Search, the DFPlayer Mini datasheet shows a standby power of 20 mA, which far too high. A forum post shows that if the sleep mode is enabled using the serial interface, current drops to 0.4 uA. This is much better.
For the 555 itself, you mention an astable oscillating configuration, although I’m wondering what your intention for the 555 is. Ostensibly, the DFPlayer either needs a brief pulse to start playing (roughly “edge triggered”) or needs to be kept active for as long as the music should be playing (roughly “level triggered”). In either case, a 555 in a one-shot configuration would make sense, since an astable oscillator would imply the music would restart on its own every so often.
If you’re insisting on the 555, then you may not be able to access the sleep mode in the DFPlayer Mini. So your option might be to gate the DFPlayer so that it only gets Vcc power when the 555 supplies it, probably using a MOSFET. Alternatively, using a cheap microcontroller would let you control the DFPlayer Mini via serial. Your microcontroller could then also receive the signal from the vibration switch and come out of deep sleep to issue commands to the DDPlayer.
The ATTiny uC and MSP430 uC families can draw as low as microamps or even nanoamps in some low-power modes. So that neatly addresses the standby current.
What you’ll also have to assess is the active current, or how much the music player draws when it runs for however long. This should give you an idea of the total lifetime for your application on a single battery charge.
Im surprised they make fans this small but i think they are really weak. Im gonna order one of them to test the airflow but i wanted to make my own one to fit more fan in a package thats good for my light. But thanks anyway im gonna try some of these. If the performance is really bad, a custom built one probably wouldnt be much better.
Replying to myself for informational reason. Modifying voltage was more or less successful. Both optocouplers transmit a reference voltage, so both need to be adjusted simultaneously.
This can be done by changing the value of R19, a 23.2k smd resistor close to the output terminals.
I’ve attached a 10k pot with a 10k and 6.8k resistor in series and successfully modified the voltage down to 22.5.
The power supply itself is a piece of crap though. It claims to handle 400W but anything over 150W causes the short circuit protection to activate, never mind overheating at 150W very quickly.
Considering there is what appears to be a fixed-stepdown 12 volt AC transformer on the line side of that board, I’d be surprised if you will change anything higher via IC’s.
This may be switch-regulated for rectification and line voltage correction but it definitely does not look modifiable.
That’s not a mains frequency transformer. Not enough steel. It’s a high-frequency all-switchmode supply.
However, that’s not to say you can simply adjust the feedback and have it safely deliver near twice the voltage. The secondary side diodes and capacitors probably won’t be up to it, or will have a very limited life.
The transformer does have a ratio, and the marking makes it clear that this is a specific part for the 12V model. How much leeway there is will depend on topology. Flyback are generally fairly flexible. Other types less so.
Starting with a 24V model and either adjusting the feedback resistors or adding a few diodes would be near trivial. Many will already have a potentiometer that provides that degree of adjustment. Starting with a 12V model is an uphill battle.
TO220 package diodes are pretty common in SMPS applications, so I’m not sure that’s a guarantee.
EDIT: Not sure what you’re getting at here? Royer doesn’t seem to need anything other than a rectifier on the secondary, and plenty of topologies use two power transistors on the primary.
The second smaller transformer below the main one does tend to suggest it could be a Royer, at least from my reading. I don’t see the extra switches needed for it to be a PFC stage.
skipped reading the silkscreen … it says Q1 on the lowermost package but the other three are diodes. so could also be a forward converter or something similar.
Well there certainly is some regulation because attaching a load does not decrease the voltage by much. Increasing the voltage is indeed ambitious for the 12V model but lowering the voltage of the 12V model seems doable.
It’s probably not a good idea for actual use, but if you’d like to experiment: looks like the 3-pin devices U4 and U5 on the upper right provide feedback through the optocouplers next to the class Y cap north of the transformer. I bet those are LM431 voltage references (or similar). The passives around them provide filtering, but two of the resistors should form a resistor divider for the Ref pin (lower right pin if the single pin is on top). That divider sets the voltage.
Thanks. I ordered the 24V model in hopes of adjusting it down to 22V. I will use that to keep a 7s Li-Ion battery at a minimum charge level whereas a solar panel array may increase that voltage higher. It looks like the 24V model’s capacitors need to be changed as well since they can’t handle the Li-Ion batterys’ max charge voltage.
Are you able to measure the input current during a weld?
I suspect you might not have enough copper in the secondary. Fully insulated wires take up a lot of space; there’s a reason magnet wire is commonly used. Several parallel turns of e.g. 6mm^2 magnet wire would be preferable.
Your SSR generally should be in the phase, not the neutral.
If it’s a 240v transformer, the primary will have less turns than a 120v one. You may not have a high enough voltage out of your new secondary because of that.
If it’s just a matter of getting a larger voltage, then you already got 400V. No need for new windings, unless the insulation on the primary can’t handle 400V.
As others have said, increasing the output by 5/6 is unrealistic. And even it would work, it’d only be for a short while. Best case is that it works and you’re home and awake when it catches fire.
Better buy a dedicated powersupply. How expensive something is, is in the eye of the beholder, but it is worth it. Most of the ones on this list can be adjusted 10 or 15% and that should get you there from 24V. And they’re actually meant to do it. dk.rs-online.com/…/switch-mode-stromforsyninger-s…
I went down this road just as you. I found out that most MOTs are rather weak for 18650 nickel strips.
You need a transformer rated around 1500 watts. Most are 700-900 watts. I ended up wiring 2 transformers in parallel. Also, make sure to remove the transformer’s shunts. They are a form of current limiting and will impact your amps at the end.
Finally, make sure to carefully regulate your pressure with the copper tips. High pressure does indeed equal a weaker weld.
AC in general is also not the best for very short pulses of welds. I have found that 40-60ms work best for 0.2 with around 1000amps. Anything less didn’t weld tbh and the MOT couldn’t pull amps fast enough. I tried all sorts of windings and cable thicknesses. I finally chose 6AWG and I’m happy enough with 2 transformers.
Depending on the power consumption, you may consider not using thermal relief while connecting thermal vias for the chip (component 57) to ground layers. But this may make soldering harder so do it only if needed. Thermal vias are so close that they form 3 long dents in 3v3 plane. It is good practice to put vias a little far apart so that planes can go through between vias. This can be important since sometimes lowest impedance can be obtained when current is flowing between those vias. If you don’t need to fit 15 vias there, you may consider reducing the number and separating them a bit. You can also check the design rules for minimum copper width and minimum via clearance for your manufacturer and enter them in your CAD tool.
Yeah don’t worry about it. Running a fan at a lower voltage than it’s meant for will result in slower fan speeds and a longer lifetime. Compared to the wattage an actual laptop will draw this is absolutely nothing. I power my soldering iron with an old laptop charger without issues.
Those plugs are generally used in 12V systems but they can handle higher voltages too. It’s the current you need to be mindful of for the most part, they can overheat if you try to power a space heater or something from that but a few fans won’t cause any issues.
I figured you already had some type of adapter already. Either the one you linked, or the DC connection from the printer. If that’s the case, then it’s ridiculously easy to do a DC to DC adapter. If you do not have a DC supply and just need a 24v power supply, splurge on something like this.
Honestly you’d probably be fine with your original idea. But, that means you can’t charge your laptop while printing and, the 24v power supply I linked to is cheaper than your original idea.
Those adapters should definitely be fine for 24 V. Running the fans off 19 V will probably work, but they will run at slightly slower RPM (probably not a big problem for a filter).
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