But if that is the case, why would it be fine during programming and testing, which literally took hours or it being in varying states of off and on but always the music was being played because we needed to sync the lighting sequence to the music. Surely, if there was such a problem it would have occurred during the testing and not in the 10-15mins of the customer having it on?Do you have an oscilloscope? If the capacitor isn't being DC voltage stressed, and isn't installed backwards, the MP3 unit may be inducing a severe radio frequency (RF) oscillation, either in itself or the voltage regulator. That could also make the decoupling cap overheat very quickly. There should be a 0.001 uF ceramic cap in parallel with the electrolytic to swamp that kind of thing, but different regulators are very sensitive to capacitive loading, and to the equivalent series resistance (ESR) of the decoupling caps. The exact device data sheet is the bible.
As I discovered yesterday, it's only hot when the MP3 player is linked so I don't think there's necessarily anything wrong with it specifically and I can't risk using the board anyway so will just do a new board.@ jensmith25 -IF- you haven't replaced the hot cap please do that - there seems to be indication that it's still installed... it may or may not help... but it's a logical first step...
Or maybe it's just drawing too much current through the regulator. The DF Player module will draw 20mA in standby and more when accessing the SD Card and/or driving the speaker.I've tested the Mp3 player on the 14m2 audio board AXE171 (running off a 4.5v battery box) and it's working fine so there must be some sort of problem when it's being plugged into the CHI030 board. Maybe it is an oscillation problem with the regulator.
Yeah, I just don't understand how it was fine when I was testing it and now it's not.Or maybe it's just drawing too much current through the regulator. The DF Player module will draw 20mA in standby and more when accessing the SD Card and/or driving the speaker.
Perhaps disconnect the regulator, power the CHI030A from the same battery box you powered the AXE171 from, and see if that solves the problem.
Admittedly it would seem odd that the regulator did not overheat during previous testing but does now.
It would be worth connecting the DF Player module back to the AXE171 to check that it is still working.
You could also power the AXE171 and DF Player through a regulator to see if that also overheats when you do.
If a TO-220 style regulator with a heatsink tab is getting warm then a transistor style regulator is likely to get even hotter. It might be worth measuring the current being drawn.Just tried running it through the AXE171 with a LM78XX PCB regulator circuit ... Regulator only mildly warm. It has a big heatsink too.
TO-92 TO-220
.---. .-------.
/ \ | O O O |
| O O O | |-------|
`-------' `-------' Tab
Out 0 In Out 0 In
I assumed mildly warm wasn't anything to worry about?If a TO-220 style regulator with a heatsink tab is getting warm then a transistor style regulator is likely to get even hotter. It might be worth measuring the current being drawn.
You could just replace the transistor regulator on the CHI030A board with a TO-220 style regulator , power the CHI030A and DF Player through that, but check the pinout first. Viewed from top, legs downwards, I think this is right ...
Code:TO-92 TO-220 .---. .-------. / \ | O O O | | O O O | |-------| `-------' `-------' Tab Out 0 In Out 0 In
Mildly warm is probably not anything to worry about. The TO-220 style of regulator is designed to carry larger currents and get somewhat hot. Smaller transistor style regulators aren't.I assumed mildly warm wasn't anything to worry about?
I would guess so.I'll try and check the current. Current drawn by what? The MP3 player?
You can use that board in place of an actual regulator on the CHI030. To save unsoldering and soldering it in to where the regulator is supposed to go you can connect it between V1 and V2 power connections at the bottom of the board.I could do that and just swap them - I wasn't sure if the pinout was the same but this other board has 4 diodes, 2 beefy capacitors and a resistor so I assumed it might be better at coping if the MP3 player is drawing more current.
Can you explain further? Do you mean gnd goes to V1 and positive goes to V2?You can use that board in place of an actual regulator on the CHI030. To save unsoldering and soldering it in to where the regulator is supposed to go you can connect it between V1 and V2 power connections at the bottom of the board.
Thanks Hippy.If you look at the circuit diagram you will see V2 goes to the on-board regulator input, its output goes to V1.
So you can remove the on-board regulator, take a wire from V2 to the off-board regulator input, take its output to V1, and connect its 0V to either V1 or V2 0V.
Okay, I thought the regulator wasn't affected by the current of the outputs, or is this specific to the MP3 player where it is drawing current from the regulator?A TO-220 voltage regulator is rated for 1 amp. However, with no added heat sink that will get warm at around 200 mA.
So if the TO-220 LM7805 regulator is getting warm the then the TO-92 78L05 rated at only 100 mA will be overloaded and hence getting very hot. In fact the 78L05 is likely shutting down or cycling on and off.
All linear regulators are affected by current drawn. It is basically 'output current times voltage dropped' which has to be dissipated and that goes as heat. So 100mA drawn from a regulator dropping 12V to 5V would be 0.1 x (12-5) = 0.7W.Okay, I thought the regulator wasn't affected by the current of the outputs, or is this specific to the MP3 player where it is drawing current from the regulator?
The 78L05 is recommended for providing current to the PICAXE on the CHI030A board when powered by greater than 5V so does not take into account current drawn by other boards using 5V from the CHI030A board.It would be good to have a warning in the instructions for the CHI030 board if there is a problem with current with the 78L05 as that's the specific one you are told to use.
All linear regulators are affected by current drawn. It is basically 'output current times voltage dropped' which has to be dissipated and that goes as heat. So 100mA drawn from a regulator dropping 12V to 5V would be 0.1 x (12-5) = 0.7W.
The 78L05 is recommended for providing current to the PICAXE on the CHI030A board when powered by greater than 5V so does not take into account current drawn by other boards using 5V from the CHI030A board.
I would guess that was presumed to be general electronics knowledge and anyone using a regulator would know that its current rating should not be exceeded and a regulator capable of supporting the current being drawn should be used if more were required. Much like not drawing too much current out of an I/O pin.
It is powered off the AXE171 supply rail, 5V or 4.5V. If you are powering it off an I/O pin on the CHI030A then that might also explain things.That obviously changes things to an extent that I wasn't aware of. I assumed, presumably incorrectly, that the MP3 player wasn't drawing that much current since there's no info on that in the MP3 instructions when it's being played and it was being powered off the AXE171 board quite happily off an I/O pin!
In normal use there usually isn't really much difference. In one case it's getting its power from the batteries, in the other it's getting its power through the regulator.I guess I don't fully understand the difference between powering it off 4.5v and why it's suddenly a problem powering it off 12v.
Around 20mA-30mA would seem as expected for the setup when not playing. Not sure why it won't play with the meter in-line. I use a bench supply which shows current drawn so am not familiar with the pro's and con's of measuring in-line.EDIT: it looks like the MP3 player is drawing 21-22mA seen a high of 30mA? Measured on MP3 player. But it wouldn't play when the multimeter was connected in series. That doesn't seem like it should be a problem?
That should work but switched mode regulators can sometimes put high-frequency ripple on the power rail which may interfere with audio circuits. There's no way to tell without trying it.The regulator is warm after playing through the whole lot which is a few minutes. I could get one of these to be sure??: It's 3Ahttps://www.ebay.co.uk/itm/Raspberry-Pi-DC-DC-Converter-Regulator-12V-Stepdown-to-5V-3A-15W-Module-Power/142752974294?epid=1274078478&hash=item213cbd85d6:g:JXQAAOSw5cNYcSC7
It's connected to the V+ and G of the strip of connection points between the Picaxe chip and the darlington driver chip. I didn't think that was off an I/O pin.It is powered off the AXE171 supply rail, 5V or 4.5V. If you are powering it off an I/O pin on the CHI030A then that might also explain things.
It wasn't easy to tell where power was connected to in your earlier photo. I assumed it was to to the V1 connection on the CHI030A.
The effect of an in-line amp meter is the series resistance it adds to the circuit. Using my cheap Craftsman DVM, in the 20A range the resistance is only 0.4 ohms. The milliamp range adds 4 ohms, and the microamp range adds about 100 ohms. Whether this matters in a particular circuit will depend on many factors, but in all cases the effect will be to reduce the voltage to the circuit under test. This reduction will equal follow Ohm's Law. V=R*IAround 20mA-30mA would seem as expected for the setup when not playing. Not sure why it won't play with the meter in-line. I use a bench supply which shows current drawn so am not familiar with the pro's and con's of measuring in-line.
I make that an 8 volt drop at 20A and a dissipation of 160 watts.in the 20A range the resistance is only 0.4 ohms.
Range Current Delta Volts Calculated R
uA 0.004 0.411 103
mA 0.400 1.560 3.9
A 1.00 0.250 0.25 on this range, the meter has a note on the face: 15sec in 30min
To include white space in a forum post, put your ASCII image in [code] ... [/code] markers, as if it was code.Crap. I see the forum software removed all my spaces. Sorry for the yukky chart.
tom