I bought the following 4A 5V supply adapter: https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors with the aim of trying it as an alternative supply for my 16 year old curtain controller circuit. At present I successfully use 3 x AA Nimh batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the battery terminals). Current consumption varies from about 2.6A to stalled at 4A or so. I was surprised to find that the adaptor does not work with the circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor *and* to the only other DC motor I have at hand, a 12V miniature drill. Here's my 'scope showing the adapter's bursts of brief action: https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 I can find other uses for this, but I'm curious to discover why it doesn't work for the intended purpose. Terry, East Grinstead, UK
Adapter fails to power DC motor
Started by ●March 3, 2020
Reply by ●March 3, 20202020-03-03
On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote:> I bought the following 4A 5V supply adapter: > https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors > with the aim of trying it as an alternative supply for my 16 year old > curtain controller circuit. At present I successfully use 3 x AA Nimh > batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the > battery terminals). Current consumption varies from about 2.6A to > stalled at 4A or so. > > I was surprised to find that the adaptor does not work with the > circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor > *and* to the only other DC motor I have at hand, a 12V miniature drill. > > Here's my 'scope showing the adapter's bursts of brief action: > https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 > > I can find other uses for this, but I'm curious to discover why it > doesn't work for the intended purpose. >I was interested in the product, so looked at the datasheet, where it says Over-Current Protection >3.6A with auto-recovery function Could it be that the protection kicks in on start current, likely to be the full stall current of aprox 4A, recovers, kicks in again, recovers, etc,etc? Jim
Reply by ●March 3, 20202020-03-03
On Tuesday, March 3, 2020 at 7:32:36 AM UTC-5, Jim Jackson wrote:> On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: > > I bought the following 4A 5V supply adapter: > > https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors > > with the aim of trying it as an alternative supply for my 16 year old > > curtain controller circuit. At present I successfully use 3 x AA Nimh > > batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the > > battery terminals). Current consumption varies from about 2.6A to > > stalled at 4A or so. > > > > I was surprised to find that the adaptor does not work with the > > circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor > > *and* to the only other DC motor I have at hand, a 12V miniature drill. > > > > Here's my 'scope showing the adapter's bursts of brief action: > > https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 > > > > I can find other uses for this, but I'm curious to discover why it > > doesn't work for the intended purpose. > > > > I was interested in the product, so looked at the datasheet, where it says > > Over-Current Protection >3.6A with auto-recovery function > > Could it be that the protection kicks in on start current, likely to be > the full stall current of aprox 4A, recovers, kicks in again, recovers, > etc,etc? > > JimHuh, 3.6 A over current on a 4 A supply is a little sneaky. Terry, I've used a bunch of Phihong power supplies... I abused 'em but only with a resistive load. I guess you need a 'bigger boat' maybe look for a 25 or 30 W supply.. (find another 5V supply in your scrap box and put two in parallel?) George H.
Reply by ●March 3, 20202020-03-03
On 3/3/2020 6:32 AM, Jim Jackson wrote:> On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: >> I bought the following 4A 5V supply adapter: >> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors >> with the aim of trying it as an alternative supply for my 16 year old >> curtain controller circuit. At present I successfully use 3 x AA Nimh >> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the >> battery terminals). Current consumption varies from about 2.6A to >> stalled at 4A or so. >> >> I was surprised to find that the adaptor does not work with the >> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor >> *and* to the only other DC motor I have at hand, a 12V miniature drill. >> >> Here's my 'scope showing the adapter's bursts of brief action: >> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 >> >> I can find other uses for this, but I'm curious to discover why it >> doesn't work for the intended purpose. >> > > I was interested in the product, so looked at the datasheet, where it says > > Over-Current Protection >3.6A with auto-recovery function > > Could it be that the protection kicks in on start current, likely to be > the full stall current of aprox 4A, recovers, kicks in again, recovers, > etc,etc? > > Jim >Sounds like it to me. I think the stalled motor inrush is causing it.
Reply by ●March 3, 20202020-03-03
On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson <jj@franjam.org.uk> wrote:>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: >> I bought the following 4A 5V supply adapter: >> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors >> with the aim of trying it as an alternative supply for my 16 year old >> curtain controller circuit. At present I successfully use 3 x AA Nimh >> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the >> battery terminals). Current consumption varies from about 2.6A to >> stalled at 4A or so. >> >> I was surprised to find that the adaptor does not work with the >> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor >> *and* to the only other DC motor I have at hand, a 12V miniature drill. >> >> Here's my 'scope showing the adapter's bursts of brief action: >> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 >> >> I can find other uses for this, but I'm curious to discover why it >> doesn't work for the intended purpose. >> > >I was interested in the product, so looked at the datasheet, where it says > > Over-Current Protection >3.6A with auto-recovery function > >Could it be that the protection kicks in on start current, likely to be >the full stall current of aprox 4A, recovers, kicks in again, recovers, >etc,etc? > >JimYes. The current limit on many warts is to quickly sense over-current, 1.5x rated maybe, shut down for some fraction of a second, and try again. The average current into a short is low. There can be problems with a wart trying to bring up an electronic device too, like a negative-input-impedance switcher, or something with big input caps. I design soft-starts into my stuff to allow the wart to get up to voltage. -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
Reply by ●March 3, 20202020-03-03
jlarkin@highlandsniptechnology.com wrote:>On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson ><jj@franjam.org.uk> wrote: > >>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: >>> I bought the following 4A 5V supply adapter: >>> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors >>> with the aim of trying it as an alternative supply for my 16 year old >>> curtain controller circuit. At present I successfully use 3 x AA Nimh >>> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the >>> battery terminals). Current consumption varies from about 2.6A to >>> stalled at 4A or so. >>> >>> I was surprised to find that the adaptor does not work with the >>> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor >>> *and* to the only other DC motor I have at hand, a 12V miniature drill. >>> >>> Here's my 'scope showing the adapter's bursts of brief action: >>> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 >>> >>> I can find other uses for this, but I'm curious to discover why it >>> doesn't work for the intended purpose. >>> >> >>I was interested in the product, so looked at the datasheet, where it says >> >> Over-Current Protection >3.6A with auto-recovery function >> >>Could it be that the protection kicks in on start current, likely to be >>the full stall current of aprox 4A, recovers, kicks in again, recovers, >>etc,etc? >> >>Jim > >Yes. The current limit on many warts is to quickly sense over-current, >1.5x rated maybe, shut down for some fraction of a second, and try >again. The average current into a short is low. > >There can be problems with a wart trying to bring up an electronic >device too, like a negative-input-impedance switcher, or something >with big input caps. I design soft-starts into my stuff to allow the >wart to get up to voltage.Prompted by Jim's suggestion I tried some hefty electrolytics in parallel, thinking they would assist startup. For example: 100,000 uF/10V, 25,000 uF/50. But same result. They were of course at the adapter's 5.1 V when I applied the motor load. Terry, East Grinstead, UK
Reply by ●March 3, 20202020-03-03
Terry Pinnell <me@somewhere.invalid> wrote:>jlarkin@highlandsniptechnology.com wrote: > >>On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson >><jj@franjam.org.uk> wrote: >> >>>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: >>>> I bought the following 4A 5V supply adapter: >>>> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors >>>> with the aim of trying it as an alternative supply for my 16 year old >>>> curtain controller circuit. At present I successfully use 3 x AA Nimh >>>> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the >>>> battery terminals). Current consumption varies from about 2.6A to >>>> stalled at 4A or so. >>>> >>>> I was surprised to find that the adaptor does not work with the >>>> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor >>>> *and* to the only other DC motor I have at hand, a 12V miniature drill. >>>> >>>> Here's my 'scope showing the adapter's bursts of brief action: >>>> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 >>>> >>>> I can find other uses for this, but I'm curious to discover why it >>>> doesn't work for the intended purpose. >>>> >>> >>>I was interested in the product, so looked at the datasheet, where it says >>> >>> Over-Current Protection >3.6A with auto-recovery function >>> >>>Could it be that the protection kicks in on start current, likely to be >>>the full stall current of aprox 4A, recovers, kicks in again, recovers, >>>etc,etc? >>> >>>Jim >> >>Yes. The current limit on many warts is to quickly sense over-current, >>1.5x rated maybe, shut down for some fraction of a second, and try >>again. The average current into a short is low. >> >>There can be problems with a wart trying to bring up an electronic >>device too, like a negative-input-impedance switcher, or something >>with big input caps. I design soft-starts into my stuff to allow the >>wart to get up to voltage. > >Prompted by Jim's suggestion I tried some hefty electrolytics in >parallel, thinking they would assist startup. For example: 100,000 >uF/10V, 25,000 uF/50. But same result. They were of course at the >adapter's 5.1 V when I applied the motor load. > >Terry, East Grinstead, UKMeant to add: while fiddling with this, tapping wires at various intervals, there was just *one* instance when the motor *did* start running at what appeared full speed. Spent another few minutes trying in vain to reproduce that.
Reply by ●March 3, 20202020-03-03
On Tuesday, March 3, 2020 at 11:53:11 AM UTC-5, Terry Pinnell wrote:> Terry Pinnell <me@somewhere.invalid> wrote: > > >jlarkin@highlandsniptechnology.com wrote: > > > >>On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson > >><jj@franjam.org.uk> wrote: > >> > >>>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: > >>>> I bought the following 4A 5V supply adapter: > >>>> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors > >>>> with the aim of trying it as an alternative supply for my 16 year old > >>>> curtain controller circuit. At present I successfully use 3 x AA Nimh > >>>> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the > >>>> battery terminals). Current consumption varies from about 2.6A to > >>>> stalled at 4A or so. > >>>> > >>>> I was surprised to find that the adaptor does not work with the > >>>> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor > >>>> *and* to the only other DC motor I have at hand, a 12V miniature drill. > >>>> > >>>> Here's my 'scope showing the adapter's bursts of brief action: > >>>> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 > >>>> > >>>> I can find other uses for this, but I'm curious to discover why it > >>>> doesn't work for the intended purpose. > >>>> > >>> > >>>I was interested in the product, so looked at the datasheet, where it says > >>> > >>> Over-Current Protection >3.6A with auto-recovery function > >>> > >>>Could it be that the protection kicks in on start current, likely to be > >>>the full stall current of aprox 4A, recovers, kicks in again, recovers, > >>>etc,etc? > >>> > >>>Jim > >> > >>Yes. The current limit on many warts is to quickly sense over-current, > >>1.5x rated maybe, shut down for some fraction of a second, and try > >>again. The average current into a short is low. > >> > >>There can be problems with a wart trying to bring up an electronic > >>device too, like a negative-input-impedance switcher, or something > >>with big input caps. I design soft-starts into my stuff to allow the > >>wart to get up to voltage. > > > >Prompted by Jim's suggestion I tried some hefty electrolytics in > >parallel, thinking they would assist startup. For example: 100,000 > >uF/10V, 25,000 uF/50. But same result. They were of course at the > >adapter's 5.1 V when I applied the motor load. > > > >Terry, East Grinstead, UK > > Meant to add: while fiddling with this, tapping wires at various > intervals, there was just *one* instance when the motor *did* start > running at what appeared full speed. Spent another few minutes trying in > vain to reproduce that.Are you switching the power at the AC input or DC output? George H.
Reply by ●March 3, 20202020-03-03
On Tue, 03 Mar 2020 16:48:57 +0000, Terry Pinnell <me@somewhere.invalid> wrote:>jlarkin@highlandsniptechnology.com wrote: > >>On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson >><jj@franjam.org.uk> wrote: >> >>>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: >>>> I bought the following 4A 5V supply adapter: >>>> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors >>>> with the aim of trying it as an alternative supply for my 16 year old >>>> curtain controller circuit. At present I successfully use 3 x AA Nimh >>>> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the >>>> battery terminals). Current consumption varies from about 2.6A to >>>> stalled at 4A or so. >>>> >>>> I was surprised to find that the adaptor does not work with the >>>> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor >>>> *and* to the only other DC motor I have at hand, a 12V miniature drill. >>>> >>>> Here's my 'scope showing the adapter's bursts of brief action: >>>> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 >>>> >>>> I can find other uses for this, but I'm curious to discover why it >>>> doesn't work for the intended purpose. >>>> >>> >>>I was interested in the product, so looked at the datasheet, where it says >>> >>> Over-Current Protection >3.6A with auto-recovery function >>> >>>Could it be that the protection kicks in on start current, likely to be >>>the full stall current of aprox 4A, recovers, kicks in again, recovers, >>>etc,etc? >>> >>>Jim >> >>Yes. The current limit on many warts is to quickly sense over-current, >>1.5x rated maybe, shut down for some fraction of a second, and try >>again. The average current into a short is low. >> >>There can be problems with a wart trying to bring up an electronic >>device too, like a negative-input-impedance switcher, or something >>with big input caps. I design soft-starts into my stuff to allow the >>wart to get up to voltage. > >Prompted by Jim's suggestion I tried some hefty electrolytics in >parallel, thinking they would assist startup. For example: 100,000 >uF/10V, 25,000 uF/50. But same result. They were of course at the >adapter's 5.1 V when I applied the motor load. > >Terry, East Grinstead, UKIf there was no load on the big cap, the supply would eventually charge it. But the start current of the motor could collapse everything when it was connected. A supercap might work. Or a better power supply. -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
Reply by ●March 3, 20202020-03-03
On Tuesday, March 3, 2020 at 9:53:11 AM UTC-7, Terry Pinnell wrote:> Terry Pinnell <me@somewhere.invalid> wrote: > > >jlarkin@highlandsniptechnology.com wrote: > > > >>On Tue, 3 Mar 2020 12:32:31 -0000 (UTC), Jim Jackson > >><jj@franjam.org.uk> wrote: > >> > >>>On 2020-03-03, Terry Pinnell <me@somewhere.invalid> wrote: > >>>> I bought the following 4A 5V supply adapter: > >>>> https://cpc.farnell.com/stontronics/t6819st/ac-dc-power-supply-5v-4a-2-1mm/dp/PW04378?st=5v%20power%20adaptors > >>>> with the aim of trying it as an alternative supply for my 16 year old > >>>> curtain controller circuit. At present I successfully use 3 x AA Nimh > >>>> batteries, delivering a voltage of about 3.8 to 4.1 V (measured at the > >>>> battery terminals). Current consumption varies from about 2.6A to > >>>> stalled at 4A or so. > >>>> > >>>> I was surprised to find that the adaptor does not work with the > >>>> circuit's ex-screwdriver 2.4 motor. It delivers the 4 A to a resistor > >>>> *and* to the only other DC motor I have at hand, a 12V miniature drill. > >>>> > >>>> Here's my 'scope showing the adapter's bursts of brief action: > >>>> https://www.dropbox.com/s/i2lu9z38s2fgzd3/AdaptorWithDrillMotor.jpg?raw=1 > >>>> > >>>> I can find other uses for this, but I'm curious to discover why it > >>>> doesn't work for the intended purpose. > >>>> > >>> > >>>I was interested in the product, so looked at the datasheet, where it says > >>> > >>> Over-Current Protection >3.6A with auto-recovery function > >>> > >>>Could it be that the protection kicks in on start current, likely to be > >>>the full stall current of aprox 4A, recovers, kicks in again, recovers, > >>>etc,etc? > >>> > >>>Jim > >> > >>Yes. The current limit on many warts is to quickly sense over-current, > >>1.5x rated maybe, shut down for some fraction of a second, and try > >>again. The average current into a short is low. > >> > >>There can be problems with a wart trying to bring up an electronic > >>device too, like a negative-input-impedance switcher, or something > >>with big input caps. I design soft-starts into my stuff to allow the > >>wart to get up to voltage. > > > >Prompted by Jim's suggestion I tried some hefty electrolytics in > >parallel, thinking they would assist startup. For example: 100,000 > >uF/10V, 25,000 uF/50. But same result. They were of course at the > >adapter's 5.1 V when I applied the motor load. > > > >Terry, East Grinstead, UK > > Meant to add: while fiddling with this, tapping wires at various > intervals, there was just *one* instance when the motor *did* start > running at what appeared full speed. Spent another few minutes trying in > vain to reproduce that.You could always try putting an NTC resistor in series as an inrush current limiter. Cheap, easy, probably works...why not?
