Electronics > Beginners
2 power supplies for a amp
mariush:
If you are willing to go with a class D amplifier, you have plenty of choices on eBay.
For example, this one is ~25$ : https://www.ebay.com/itm/Mini-Class-D-Power-Amplifier-HiFi-Stereo-2-0-Channel-Digital-Audio-Amp-50W-50W/262315996089
It uses a TPA3116D2 : http://www.ti.com/lit/ds/symlink/tpa3118d2.pdf
which can do :
2 × 50 W Into a 4-ΩBTL Load at 21 V
2 × 30 W Into a 8-ΩBTL Load at 24 V
2 × 15 W Into a 8-ΩBTL Load at 15 V
Has the added bonus of a volume knob, and you can power it using a plain wallwart adapter. I think it has a standard 2.5mm barrel jack... either 2.1mm or 2.5mm
19$ gets you an 18v 60w adapter: https://www.digikey.com/product-detail/en/mean-well-usa-inc/GST60A18-P1J/1866-2151-ND/7703714
34$ gets you 24v 90w : https://www.digikey.com/product-detail/en/mean-well-usa-inc/GST90A24-P1M/1866-2157-ND/7703720
44$ gets you 24v 120w: https://www.digikey.com/product-detail/en/delta-electronics/DPS-120AB-3-B/941-1788-ND/6561830
vol.2:
--- Quote from: mariush on September 26, 2019, 02:57:17 am ---If you are willing to go with a class D amplifier, you have plenty of choices on eBay.
For example, this one is ~25$
--- End quote ---
Thanks for your alternative suggestion.
I also considered a class D unit. I watched some various tear-downs of the cheap ebay stuff on youtube.
About the particular unit you linked to, this one review claims that the choice of output filter coils is optimized for 8 ohm loads and that lower impedance loads experience roll-off in higher frequencies. If you see at 12:33:
However, there is this other board here: https://www.ebay.com/itm/392072722443?ul_noapp=true
That board seems to be a little better and draws about 1.75A at 20VDC:
I could probably use a laptop supply with it. I have an orphaned toshiba laptop PSU that does 19VDC 6A. Maybe I should just get two of those mono D boards and split the laptop PSU to both of them?
Thanks,
Zero999:
--- Quote from: wraper on September 25, 2019, 11:45:09 pm ---
--- Quote from: Zero999 on September 25, 2019, 04:49:38 pm ---That power supply will probably do the job, but you forgot to post the data sheet for the amplifier, so we don't know how much current it requires.
Another option is to use two 24V supplies in series and take the 0V from when they join. Connecting a couple of diodes in parallel with each of them is a good idea to prevent either supply from seeing to higher negative voltage, if it current limits or shuts down. The diodes should be rated to a bit more current, than the power supply's rating.
Having more than one 0V connection is pretty common.
(Attachment Link)
--- End quote ---
You need to be cautious with that. Not every PSU will be fine with that, some may have resistor to earth from negative output or even direct connection. Connecting such PSUs in series may cause magic smoke escaping.
--- End quote ---
Yes, that's very true. The original poster should check the power supplies are floating first, before connecting their outputs in series.
vol.2:
--- Quote from: Zero999 on September 26, 2019, 08:06:19 am ---Yes, that's very true. The original poster should check the power supplies are floating first, before connecting their outputs in series.
--- End quote ---
Thanks. I checked the data sheet and it does look like the - side is tied to ground.
Can you tell me if i can split a 19v switching laptop supply into two so I can power two mono amp boards like the one I linked above?
Zero999:
--- Quote from: vol.2 on September 26, 2019, 06:21:01 pm ---Can you tell me if i can split a 19v switching laptop supply into two so I can power two mono amp boards like the one I linked above?
--- End quote ---
I'm not sure what you're asking.
When you mean split, a 19V supply, which would give +/-9.5V, or use two 19V supplies for +/-19V?
Splitting a single 19V supply is possible with a virtual earth/ground circuit, but if you want to connect it to external devices, with grounded chassis, you need to check the 19V supply is floating.
Connecting two 19V supplies in series for +/-19V is only possible if they're floating. Laptop power supplies vary. Some are floating, others are not. One thing you can do is check what sort of mains connector, the power supply uses. If it's three pole, it will have an earth connection and might not be floating. If it's two pole, then there's now way it's grounded and has to be floating.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version