Electronics Lab Philippines

Electronic Bongos

Offline Super zHero

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Re: Electronic Bongos
« Reply #80 on: October 07, 2020, 12:43:02 PM »
With the values of R1, R2 & C2 in the schematics and PCB layout, the output freq is about 315Hz.  The ripple of the charge pump output voltage came to around 232mVpp as shown here:


Offline Super zHero

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Re: Electronic Bongos
« Reply #81 on: October 07, 2020, 12:58:09 PM »
On my solderless prototype, the value of R2 was 20K and C2 was 4.7nF (472), so my freq was about 6.8kHz.  I don't have 4.7nF in 1206 SMD so I just used 10nF or 0.01uF on this version.  The freq is around 3kHz:



The ripple is down to less than 74mVpp as shown above with a 1K load resistor.

Offline Super zHero

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Re: Electronic Bongos
« Reply #82 on: November 16, 2020, 08:07:02 PM »
I found this on Shopee.  I think I'll order some and give them a try.  Only P128 ea:



3-15Vdc in, -12Vdc out.

Offline Super zHero

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Re: Electronic Bongos
« Reply #83 on: November 25, 2020, 03:23:46 PM »
Just came in from Shopee via J&T.  I ordered it Nov 16:



Need to test it next.

Offline Super zHero

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Re: Electronic Bongos
« Reply #84 on: November 27, 2020, 10:40:11 AM »
The backside of the -12V converter PS from Shopee.  Header pins not included:



Just to compare this with my homemade 555 circuit:



It's about half the size of the 555 circuit, more stable and regulation stays at -12V from 3.7V to 15Vdc in.  A little expensive at Php128.00, but it does to job.

Offline insomartin

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Re: Electronic Bongos
« Reply #85 on: November 28, 2020, 07:55:23 PM »
madami akong ginawang synth pre-elab days. :( lahat wala na. but gagawa din ako siguro. i have some transimpedance amplifiers for limiters/compressor projects sa bin.

Offline Super zHero

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Re: Electronic Bongos
« Reply #86 on: Yesterday at 09:54:08 PM »
Just received this from Shopee this afternoon:



It's a +/-12Vdc PS.  Specs are:

1. Input voltage range: 2.8V ~ 5.5V
2. Output voltage: 12V
3. Output Current: + 12V, 50ma; -12V, 30ma

Offline Super zHero

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Re: Electronic Bongos
« Reply #87 on: Yesterday at 10:32:11 PM »
I found out that the SOT23-5 IC used here is a TI TPS6104x Low Power DC-DC Boost Converter.  If you look in the Datasheet you'll find their sample circuit for the +/- output.

Each board cost only Php45 from the Shopee supplier.