Gents,
I do not understand why are you focusing on 317/337 regulators? Good at DC only these are notoriously slow and noisy when supplying currents changing at audio frequencies. Load transient spec is 3V output change min load to max load. Crickey, I use the old uA78L0xx with large output capacitors for better results.
Much better choices are found with the current generation of low drop out devices. My preference is for LT1085 or REG103 etc for low cost even tho these have been around for a while now. Load transient spec is 10mV output change min load to max load.
Or for top shelf performance try LT3081. Noise and transient specs in the microvolts. Very low output impedance to frequencies above 100k.
John
I do not understand why are you focusing on 317/337 regulators? Good at DC only these are notoriously slow and noisy when supplying currents changing at audio frequencies. Load transient spec is 3V output change min load to max load. Crickey, I use the old uA78L0xx with large output capacitors for better results.
Much better choices are found with the current generation of low drop out devices. My preference is for LT1085 or REG103 etc for low cost even tho these have been around for a while now. Load transient spec is 10mV output change min load to max load.
Or for top shelf performance try LT3081. Noise and transient specs in the microvolts. Very low output impedance to frequencies above 100k.
John
cheap stuff
We are a diy forum helping each other,Im wary of claims making this and that out to be the next best thing since sliced bread.Try it if its no good inform others.😉.
alan
We are a diy forum helping each other,Im wary of claims making this and that out to be the next best thing since sliced bread.Try it if its no good inform others.😉.
alan
Yes, it may be. Or it may be genuine - and perhaps good.
Someone buy it, test it and inform about it. That's it.
Sorry for disturbing the threat.
Well actual size is not a concern. The IC chip size is actually very very small and not to be misled by the casing size. 1A output will not generate too much heat with the latest technology and most regulator can function at around 80 degrees without any issue.
Looking at the application diagram in the datasheet, it looks very simple to build your own. Chip itself seems to be about $5 in US.
Pete
Pete
Yes it is very easy to build but in the UK here the chip alone costs £8-9, quite expensive
The assembled regulator sold at £13 in eBay is therefore quite reasonable to me.
Yes it is very easy to build but in the UK here the chip alone costs £8-9, quite expensive
The assembled regulator sold at £13 in eBay is therefore quite reasonable to me.
£4.55 in Farnell 😉
TPS7A4700RGWT - TEXAS INSTRUMENTS - LDO, 3 TO 36VIN, 1A, RF, 20VQFN | Farnell United Kingdom
http://www.ti.com/lit/ds/symlink/tps7a4700.pdf
Maybe some one could look at data sheet and enlighten me.
Meaningless to me 😕
Can't find the Negative Volt equivalent either
Just go through the graphs and they are easy to interpret 😉
For the negative volt equivalent try to look for datasheet of TPS7A33 🙂
Just noticed the same seller of eBay has listed -ve low noise regulators with -5v; -12v and -15v:
TekDevice -12V 1A 16uVrms Ultra Low Noise LDO Negative Voltage Regulator 7912 | eBay
The chip used is TI TPS7A33 but the noise level is a bit higher than than +ve regulator (4uV) which is 16uV.
May try out the +/- 15V for the opamps when my two +5V ones have arrived and tested.
TekDevice -12V 1A 16uVrms Ultra Low Noise LDO Negative Voltage Regulator 7912 | eBay
The chip used is TI TPS7A33 but the noise level is a bit higher than than +ve regulator (4uV) which is 16uV.
May try out the +/- 15V for the opamps when my two +5V ones have arrived and tested.
Can anyone confirm how the VR changes the laser voltage - it isn't obvious whether the resistor will increase the potential or not, turning clockwise or anticlockwise... I've swapped an original VAM1201 for a 1202, but it may not be calibrated correctly.
I have a bit of skipping and some undetected discs - I have a box set where some of the discs play and others won't. Also minor skipping problems...
It doesn't... change the voltage that is. The preset alters the feedback from an inbuilt photo detector (its on the same die as the laser diode). That feedback sets the optical output of the laser (by altering the current). The only correct way to set the laser current is with a laser power meter.
If your player has problems then you need to look at rf signal on a scope as a first check and see whether that shows any problems.
Laer pickups are (should) be supplied factory set but unfortunately there are now a lot of poor quality copies around. If its a genuine Philips then do not touch the settings.
I only adjust the VR on old laser which has pick-up problem but certainly NOT on NEW LASERS. What I did was to slightly increase or decrease the VR by slightly turning it clockwise or anti-clockwise. By try and error I did save a number of almost dead laser and make them work again. Another effective means is to adjust the height of the rotating disc to increase or decrease the gap distance between the CD and the laser head. In many cases I can make the laser work again but you need to do it by try and error as well. Good Luck.
How do you adjust the height relative to the laser? I saw no obvious way to do that - the cone seems to be fixed on the motor spindle.