On Mon, 15 May 2017 09:49:45 -0500, Dave M wrote:> Has anyone used any of the consumer-grade audio power amps such as the > LM1825, TDA2030, or TDS7297 as a basic DC power opamp? > Any reason they shouldn't be used as power supply regulators, TEC > controllers, etc? > > Dave MIf the super-est best-est performance isn't an issue, a plain old op-amp driving an emitter follower stage often works well, particularly in a 1- quadrant amplifier such as a regulator or TEC controller. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
Using consumer-grade power amp as Power opamp
Started by ●May 15, 2017
Reply by ●May 15, 20172017-05-15
Reply by ●May 15, 20172017-05-15
On Mon, 15 May 2017 10:08:20 -0700, John Larkin <jjlarkin@highland_snip_technology.com> wrote:>On Mon, 15 May 2017 16:46:44 GMT, Jan Panteltje ><pNa0nStpealmtje@yahoo.com> wrote: > >>On a sunny day (Mon, 15 May 2017 09:17:13 -0700) it happened John Larkin >><jjlarkin@highlandtechnology.com> wrote in >><aukjhchaghn3mtoc0oub3gne03c7uf7n6a@4ax.com>: >> >>>I used an old classic coil, and discharged an oil cap into it with a >>>thyratron tube. The spark climbed over the insulator back to the >>>primary terminals, so I had to add an oil-filled extension tube. >>> >>>Messy. >> >>These days it is so easy: >> http://www.ebay.com/itm/141077605344 >> >>I have one, but do not think it really is 400 kV. > >400K Chinese volts. You have to factor in the exchange rate.Sno-o-o-o-ort >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Thinking outside the box... producing elegant solutions. "It is not in doing what you like, but in liking what you do that is the secret of happiness." -James Barrie
Reply by ●May 15, 20172017-05-15
On Mon, 15 May 2017 12:48:08 -0500, Tim Wescott <seemywebsite@myfooter.really> wrote:>On Mon, 15 May 2017 09:49:45 -0500, Dave M wrote: > >> Has anyone used any of the consumer-grade audio power amps such as the >> LM1825, TDA2030, or TDS7297 as a basic DC power opamp? >> Any reason they shouldn't be used as power supply regulators, TEC >> controllers, etc? >> >> Dave M > >If the super-est best-est performance isn't an issue, a plain old op-amp >driving an emitter follower stage often works well, particularly in a 1- >quadrant amplifier such as a regulator or TEC controller.Or an opamp driving the adjust pin of a 3T regulator. That has some nice points. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●May 15, 20172017-05-15
Dave M wrote: ----------------> Has anyone used any of the consumer-grade audio power amps such as the > LM1825, TDA2030, or TDS7297 as a basic DC power opamp? >** Generally they are not unity gain stable. Audio power amps have a voltage gain of 10 to 50 times in most cases. ..... Phil
Reply by ●May 15, 20172017-05-15
George Herold wrote: -------------------------> On Monday, May 15, 2017 at 10:49:56 AM UTC-4, Dave M wrote: > > Has anyone used any of the consumer-grade audio power amps such as the > > LM1825, TDA2030, or TDS7297 as a basic DC power opamp? > > Any reason they shouldn't be used as power supply regulators, TEC > > controllers, etc? > > > > Dave M > > Only the TDA2030 comes up in a search (as obsolete) check your part numbers. >** Dave's list is full of typos. It should read: LM1875, TDA2030 and TDA7294 .... Phil> I'm guessing the DC performance is not as good as it could be. > Lots of DC offset perhaps. > > George H.
Reply by ●May 15, 20172017-05-15
Dave M wrote...> Has anyone used any of the consumer-grade audio power amps ...Sorry, but these days "consumer-grade audio power amps" are all class-D. In general most of these can perform as well as a linear amps. I have my favorites. Especially high-performance ICs that are well represented in complete PCBs from China, available at rock-bottom prices on eBay. An example, IRS2092. This Intersil PWM IC has +/-100V range, can be pushed to 1MHz, and provides 1A gate drive to a pair of n-channel HV MOSFETs. A popular combo: a 250W amplifier using an IRFI4019: two 150V, 6A FETs in a TO-220F-5 package. E.g., eBay item 122463174432 for $20 + $3 shipping. These can be DC coupled by bypassing the AC coupling capacitor. This item, an L15DSMD 250W amp, is based on IR's IRAUDAMP7S. http://i.ebayimg.com/images/g/lgEAAOSww3tY6ml0/s-l1600.jpg Recommended supply with 8-ohm speakers, +/-50V. But given the IRFI4019's rating, you'd want to stay under +/-65V. Another combo, IRS2092 + two IRFB4227: 200V, 45A TO-220 FETs, for a 1000-Watt amplifier, eBay item 222177230692, $63+$10. -- Thanks, - Win
Reply by ●May 15, 20172017-05-15
On 15 May 2017 18:42:48 -0700, Winfield Hill <hill@rowland.harvard.edu> wrote:>Dave M wrote... >> Has anyone used any of the consumer-grade audio power amps ... > > Sorry, but these days "consumer-grade audio power amps" > are all class-D. In general most of these can perform as > well as a linear amps. I have my favorites. Especially > high-performance ICs that are well represented in complete > PCBs from China, available at rock-bottom prices on eBay.Define "consumer grade". Class-AB amplifiers are the norm in automotive applications.> > An example, IRS2092. This Intersil PWM IC has +/-100V range, > can be pushed to 1MHz, and provides 1A gate drive to a pair > of n-channel HV MOSFETs. A popular combo: a 250W amplifier > using an IRFI4019: two 150V, 6A FETs in a TO-220F-5 package. > > E.g., eBay item 122463174432 for $20 + $3 shipping. These > can be DC coupled by bypassing the AC coupling capacitor. > This item, an L15DSMD 250W amp, is based on IR's IRAUDAMP7S. > http://i.ebayimg.com/images/g/lgEAAOSww3tY6ml0/s-l1600.jpg > Recommended supply with 8-ohm speakers, +/-50V. But given > the IRFI4019's rating, you'd want to stay under +/-65V. > > Another combo, IRS2092 + two IRFB4227: 200V, 45A TO-220 FETs, > for a 1000-Watt amplifier, eBay item 222177230692, $63+$10.
Reply by ●May 16, 20172017-05-16
I am having a hard time figuring out why anyone would want to do that. Just a simple circuit would be cheaper. Single ended, transistor or whatever fed by an OP AMP or even a comparator of discrete components.
Reply by ●May 16, 20172017-05-16
On a sunny day (Tue, 16 May 2017 10:14:38 +1000) it happened Clifford Heath <clifford.heath@gmail.com> wrote in <CgtSA.12714$YU2.8893@fx20.iad>:>On 16/05/17 03:08, John Larkin wrote: >> On Mon, 15 May 2017 16:46:44 GMT, Jan Panteltje >> <pNa0nStpealmtje@yahoo.com> wrote: >> >>> On a sunny day (Mon, 15 May 2017 09:17:13 -0700) it happened John Larkin >>> <jjlarkin@highlandtechnology.com> wrote in >>> <aukjhchaghn3mtoc0oub3gne03c7uf7n6a@4ax.com>: >>> >>>> I used an old classic coil, and discharged an oil cap into it with a >>>> thyratron tube. The spark climbed over the insulator back to the >>>> primary terminals, so I had to add an oil-filled extension tube. >>>> >>>> Messy. >>> >>> These days it is so easy: >>> http://www.ebay.com/itm/141077605344 >>> >>> I have one, but do not think it really is 400 kV. >> >> 400K Chinese volts. You have to factor in the exchange rate. > >Hah! It also says "1-2cm arc" which translates to 10-20kV in dry air. >That sounds possible.Indeed.
Reply by ●May 16, 20172017-05-16
On 16/05/2017 09:59, Phil Allison wrote:> Dave M wrote: > > ---------------- >> Has anyone used any of the consumer-grade audio power amps such as the >> LM1825, TDA2030, or TDS7297 as a basic DC power opamp? >> > > > ** Generally they are not unity gain stable. > > Audio power amps have a voltage gain of 10 to 50 times in most cases. >Yes, that is a consideration. The "noise gain" needs to be high but not necessarily the gain from the input of the circuit as a whole. You can of course lower the gain back to unity by attenuating the input, or a number of other tricks. The TDA2030 and similar ones also need a series R-C from the output to ground, I think it is called a "Zobel network". Usually the capacitor is 100nF or so, and the resistor 1 Ohm or so. Without this it can oscillate. The DC offset voltage is also pretty terrible and unstable with temperature. The quiescent supply current of the TDA2030 is also quite high and could be a problem in some applications. I have used TDA2030 chips in electroplating power supplies, configured as Howland current sources. I also used similar ones in voice coil drivers using an old hard driver voice coil as an actuator, and for driving power LEDs with a controlled current waveform. The reason why I used these audio amplifier chips is because they were very cheap and quite powerful. The TDA2030 is discontinued now. It was one of my favourite parts, not because it was easy to use but I guess because I got a lot of use out of them (e.g. as a kid I connected one to my crystal radio for driving a speaker) and they were very cheap so they seemed like a good deal.
