Boost Regulator Modules and Circuits.

[Skippy]

If the '6009' module is the one pictured in an earlier post, there's some possible output ripple improvements by modifying the board slightly. If the large-value ceramic cap is fitted between the rectifier diode cathode and pin 1 of the IC that would be best. Then re-fit the 220u electrolytic so the -ve terminal goes to pin 1. Then take the 0 Volt output from pin1 or as near as possible. Replacing the electrolytic with a better quality one would also be worth doing, something that has low ESR/ ESL, high ripple current rating, SMPSU suitable.

[Old cart]

I now have a couple of the XL6009 400kHz modules to experiment with. I set one up with an 8V input from a bench psu and an 82 ohm wirewound 5W resistor as load. The output voltage was set with the trimmer to 15V. A scope was connected across the load resistor and the following waveform observed.
[ATTACH]37434[/ATTACH]
This shows the ripple on the output of 250mV pk -pk, which I would consider excessive for my application and would likely cause problems. The main capacitor across the output is 220uF and there is a smaller ceramic for HF bypassing near the converter IC. The addition of a 10uF ceramic cap across the output terminals makes a large difference.
[ATTACH]37435[/ATTACH]
Adding a 68uH choke and another 10uF ceramic to make a Pi network brings the conducted noise right down. Note the change in vertical sensitivity to 10mV.
[ATTACH]37436[/ATTACH]
The 68uH choke may not be optimum but it is only 0.3 ohms resistance and I happened to have a few on hand.

Even with their bias problem ceramic capacitors seem to be the most effective in killing the noise.

Eric.

Eric it will be interesting to see how this regulator responds when hit by the coil current pulses.

[ivconic]

I now have a couple of the XL6009 400kHz modules to experiment with. I set one up with an 8V input from a bench psu and an 82 ohm wirewound 5W resistor as load. The output voltage was set with the trimmer to 15V. A scope was connected across the load resistor and the following waveform observed.
[ATTACH]37434[/ATTACH]
This shows the ripple on the output of 250mV pk -pk, which I would consider excessive for my application and would likely cause problems. The main capacitor across the output is 220uF and there is a smaller ceramic for HF bypassing near the converter IC. The addition of a 10uF ceramic cap across the output terminals makes a large difference.
[ATTACH]37435[/ATTACH]
Adding a 68uH choke and another 10uF ceramic to make a Pi network brings the conducted noise right down. Note the change in vertical sensitivity to 10mV.
[ATTACH]37436[/ATTACH]
The 68uH choke may not be optimum but it is only 0.3 ohms resistance and I happened to have a few on hand.
Even with their bias problem ceramic capacitors seem to be the most effective in killing the noise.
Eric.

That's very informative!
I haven't noticed any problems on my PI, most probably because it has very good "filtration" at its power supply stage.
But it is obvious that was just lucky coincidence in that particular case.
Now with your discovery we will have good guideline what to do if using XL6009 in further works.
Yes it is complete truth; ceramic capacitors are well known from the "radio" days, to be ultimate noise suppressors.
I am only a bit wandering about proper choke value. Chebyshev filter calculator can help here.
Have an idea; there are lot of chokes on scraped laptop motherboards, exactly having the same role there.
Would be good to test them.
http://educypedia.karadimov.info/ele...torsfilter.htm

[Ferric Toes]

Eric it will be interesting to see how this regulator responds when hit by the coil current pulses.

That is still to be investigated, as is which to choose, XL6009 or the MT3608. So far, I have the MT3608 in my viscosity meter, which is based on a low current PI arrangement. The MT3608 develops 15V which I then pass to a 12V linear regulator which in turn supplies the TX. The output of the linear regulator is low noise, but how low I have yet to measure. I have 10uF ceramic caps on both input and output of the MT3608 in addition to whatever is on the board. The module is encased in a small plastic box and wrapped with copper tape which is grounded. This is to prevent radiated noise. The linear reg. just has 1uF polyester caps on input and output.

I notice that the input caps on the XL6009 vary between suppliers. Some have 100uF and some, 220uF. I haven't yet tried ceramics on the input with the latter, but I did find that with the MT3608 these were beneficial in reducing radiated noise from the batteries.

Eric.

[Ferric Toes]

I am only a bit wandering about proper choke value. Chebyshev filter calculator can help here.
http://educypedia.karadimov.info/ele...torsfilter.htm

Many thanks. That looks like a valuable webite. Maybe that residual ringing I see is due to the choke not being optimum.

Eric.

[daverave]

ive just installed one of these voltage converters in another one of my home built detectors using three li-ion 3.7v batteries and no interference from converter to detector....im pleased cause when i went to test on beach i found a nice ring that others had missed with their minelabs and dual fields

[Old cart]

Adding a 68uH choke and another 10uF ceramic to make a Pi network brings the conducted noise right down. Note the change in vertical sensitivity to 10mV.

The 68uH choke may not be optimum but it is only 0.3 ohms resistance and I happened to have a few on hand.

Even with their bias problem ceramic capacitors seem to be the most effective in killing the noise.

Eric.[/QUOTE]
That very slight remaining noise looks to be in the range of 2MHz. If you want to reduce it very short leads and low impedance grounds are in order. Some of it may be due to the wirewound resistor you are using as load. There may be enough parasitic capacitance in parallel that it is acting as tuned circuit and it is picking up radiated noise. Also your scope probe should use a very short ground lead., maybe even a ground widget. If you don't have one you can take a length of fine wire and wrap it around the ground barrel. It looks like you have a TEK 2445/65 so you may be using P613x probes. If so remove the hook tip and the then unscrew the outer plastic barrel. Then wrap the wire tightly around the exposed metal ground barrel and trim it as short as practical.

[6666]

The one I have on my watchlist ATM is finetech007, the last ones i bought were from koala-ok.
Na mate, they ain't faked. Just scammers jacking the prices up- that's why despite my best intentions to support local businesses, I usually end up buying OS. From memory Trustfire 5000mA 18650's are about the same price, but cost $8 each locally.

Hi Tim
my li-mn cells arrived today from that finetech007 seller and they are fake, supposed to be 2500maH
Did a discharge test down to 2.98 v at 500ma and they test to only 518 maH
will be demanding my money back from this seller

[Tim]

2,98v? Aren't they 3.7v minimum? Did you fully charge them first? What sort of charger? (I just use my cheapo li-ion charger.) How long did you discharge for@500ma?
Even the shagged ones I have are still running my XR71 at longest pulse width, with no depth loss. Even the shagged ones never register below 3.8v when flat????(when removed from an e-cig). Even one that went through the washing machine pumps up to 4.15, and lasts over a day on an e-cig. (A brutal regime far exceeding MD draw).
I did buy mine from koalaok, not finetech. But I have doubts they would be different.
No-one likes to get stiffed- that's specifically why I don't buy much here in OZ.
It has been my experience that most accusations about fakes and inferior products coming from China are generally old wives tales and slander, and the products sold here at inflated prices are identical.
Once you get your money back, you will be able to use them anyway, as a PI will only draw about 150-250ma max.
Sorry for any inconvenience my ignorance, opinion, bias, or advice, may have caused you.

[daverave]

i bought li-ion 6000 mah 3.7v batteries made in china....when tested they were only around 800 mah....ive been ripped off several times by chinese fake batteries.

[6666]

2,98v? Aren't they 3.7v minimum? Did you fully charge them first? What sort of charger? (I just use my cheapo li-ion charger.) How long did you discharge for@500ma?
Even the shagged ones I have are still running my XR71 at longest pulse width, with no depth loss. Even the shagged ones never register below 3.8v when flat????(when removed from an e-cig). Even one that went through the washing machine pumps up to 4.15, and lasts over a day on an e-cig. (A brutal regime far exceeding MD draw).
I did buy mine from koalaok, not finetech. But I have doubts they would be different.
No-one likes to get stiffed- that's specifically why I don't buy much here in OZ.
It has been my experience that most accusations about fakes and inferior products coming from China are generally old wives tales and slander, and the products sold here at inflated prices are identical.
Once you get your money back, you will be able to use them anyway, as a PI will only draw about 150-250ma max.
Sorry for any inconvenience my ignorance, opinion, bias, or advice, may have caused you.

Hi Tim no need to apologise for anything, its these damn crooks on fleabay that need to apologise
I have several chargers the best being a real micro processor BMAX B6, on protected 18650 cells the max cutoff charge is 4.2 volts
and the minimum discharge is about 2.75 volts, which is considered flat, but I have the BMAX set to 2.95 volts cutoff.
As soon as I took the cells out of the packet I knew they were fake by the light weight and they "tink" when you tap the cases together, meaning they are hollow or filled with flour or similar, yes they were charged to 4.2 volts and discharged at 500 ma and got down to 2.98 volts after 62 minutes, and only recorded on the BMAX as 518 maH , so out of five 18650 buys, 3 have been fakes.

[Old cart]

That is still to be investigated, as is which to choose, XL6009 or the MT3608. So far, I have the MT3608 in my viscosity meter, which is based on a low current PI arrangement. The MT3608 develops 15V which I then pass to a 12V linear regulator which in turn supplies the TX. The output of the linear regulator is low noise, but how low I have yet to measure. I have 10uF ceramic caps on both input and output of the MT3608 in addition to whatever is on the board. The module is encased in a small plastic box and wrapped with copper tape which is grounded. This is to prevent radiated noise. The linear reg. just has 1uF polyester caps on input and output.

I notice that the input caps on the XL6009 vary between suppliers. Some have 100uF and some, 220uF. I haven't yet tried ceramics on the input with the latter, but I did find that with the MT3608 these were beneficial in reducing radiated noise from the batteries.
r
Eric.

To get noise even lower for the first stage amp the following circuit looks interesting.

http://www.wenzel.com/documents/finesse.html

[KingJL]

If I am going to have to modify one for use, I am going with the MT3608, with a LM317 current limiter set to about 1.2 A.