Author Topic: Feeltech FEELTECH FPA0510S power amplifier for signal generator  (Read 1277 times)

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Offline CosteCTopic starter

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TL;DR: Don't.

Long story:
I needed amplifier for signal generator. Something in ballpark of +/- 10 V 1 A, 100 kHz.
I found FEELTECH FPA0510S, but failed to find datasheet, jet this power amplifier had appealing size, parameters and price. It requirers only +12VDC - nice. Power rating is 1.25 A on label.

Mechanical: Overally small. Enclosure is fine, design is sensible, for price at least.  Bottom is not flat: screw stick out, holes are not deburred. Adding heatsink will be irritating.
PCBA: Soldering is OK-ish, flux remains here and there. Component placement is rather horrible, resulting in nothing exactly matching anything. Not for anybody with even slight OCD.
PCB design is poor: Footprints are too small, not fitting real parts. Crowded components and large empty areas. Component sizes seem random.

Electrical: Input, output and power input share same GND/minus potential. Heatsink it GND connected, internally with one screw. Can be changed quite easily. One can imagine short circuit from TDA2030 thermal pad to enclosure/GND.
Electronics It is, as I suspected build around TDA2030. Negative voltage is generated with LM2596S-ADJ. TDA2030 is powered directly from input +12 VDC and generated -12 VDC. 2x2200 uF inside seems a lot. No other filtering than couple of ceramic chip capacitors. RUN and PWR LEDs does not seem to do anything, despite SMPS seem to have some extra circuitry like UVLO.

Tests:
System is DC coupled as advertised.
All tests done with 100 Ohm load (not at full load of 1-2 A depending on seller)
DC offset is around 20 mV.
Bandwidth: at Gain 1x, input 1 V, -3 dB bandwidth is around 467 kHz. Risetime/falltime around 2 us @ 10 V amplitude. Graph has some artefacts (sorry)
HORRIBLE noise at 153 kHz coupled from PSU. See screenshoots.
Coil and negative voltage capacitor (C6) are noticeably warm, despite total power consumption of 0.17 A.
This gives some hope for upgrade/repair...
 

Offline makerman

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Re: Feeltech FEELTECH FPA0510S power amplifier for signal generator
« Reply #1 on: August 26, 2023, 12:59:53 pm »
Thanks, was thinking about buying one.

Looking at this instead now :

https://tinyurl.com/45kr437s


 

Offline makerman

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Re: Feeltech FEELTECH FPA0510S power amplifier for signal generator
« Reply #2 on: August 26, 2023, 01:00:44 pm »
I think i remember feeltech doing a badly built function generator also, which is why i searched before buying, the name rang a bell.
 

Offline nctnico

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Re: Feeltech FEELTECH FPA0510S power amplifier for signal generator
« Reply #3 on: August 26, 2023, 01:05:09 pm »
Thanks, was thinking about buying one.

Looking at this instead now :

https://tinyurl.com/45kr437s
That one likely has the same design & 'problem'. Filtering noise from a step-up converter like that isn't easy. If you want to fix this, then replace the step-up converter with one that switches at a much higher frequency (>500kHz) and add input and output filtering.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Online Kean

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Re: Feeltech FEELTECH FPA0510S power amplifier for signal generator
« Reply #4 on: August 26, 2023, 04:01:04 pm »
There are a few topics here about the Juntek DPA-1698 and DPA-2698 that are probably worth a read.

e.g. https://www.eevblog.com/forum/testgear/awg-buffer-amp/
 
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