I have just installed a 24v 3.6A linear power supply for my G42 with Pulsar2 to replace a switch mode supply.

If I set my tracking and stop currents above 800mA the new supply shuts down when I wake up the mount. It runs OK at 750mA or even 800mA tracking and stop currents, but anything higher than that will shut down the power supply.

The power supply as I said is rated at 3.6A, and has an automatic current limit/foldback circuit which operates at a nominal of 20% above maximum rated output, i.e. about 4.3A. I can only assume that the surge on wake up is sufficient to operate the current limit/foldback circuit.

I have used a meter to check the voltage and currents on load, and have seen currents of 4.2A on wake up using a digital meter with a 12v battery. The transient surge is likely to be higher than I am seeing on the meter.

The problem only occurs on waking up the mount as I don't see such high current drawn when the mount is in use.

The recommended power supply from the manual is 24v at 3A. The recommended setting for imaging, again from the manual, is 950ma for tracking and the same 950ma for stop current.

Are these large start-up currents expected? Has anybody else experienced the same problems?

Is anyone using a successfully using a G42 with Pulsar2 with a linear power supply? If so what supply is it?

Regards


Peter

Peter,

While I have been using Pulsar1, I have used it with 24V.

However then I have moved to Pulsar2 and after duscussion with Mr. Andras, I think 12V is recomended for Pulsar2.

Best regards,
David

Hi!

May be 0.5 ohm resistor in series will prevent the power supply from tripping. But this will not be a good permanent solution since the voltage will not be stable and will depend on the amount of current drawn from the supply. Andras said to me that they were working on a new firmware release that would work better with a 24 V supply. However, I have not experienced problems running from a 24 V supply after tightening the RA-brake a bit, preventing the RA-axis from slipping during tracking. I have also run the mount on a 16 V Li-ion battery pack with no problems.

Well, this answer is not of much help to you I guess. There is a general problem with loads that draw such big surge current at turn-on .

Keep us posted!

Best regards

Oivind Tangen

Thanks to you both for the input. It seems that there is a known problem here.

Does anybody know the maximum current the surge will take at 12v and 24v?

I can get a 12v linear supply in the same case size as my 24v supply. The 12v supply is rated at 5.1A which should not trip until 6A. Do you think this would work?

Peter

Hi Peter,

Our experience here at Ecliptica Observatory is that indeed with 24v, OPulsar2 is not running nicely, with ugly sounds and failkures like you have described. We have used 12v stabilized power now and everything is runing just great. In fact we do not see why we would use 24v anymore as even with a payload of appr. 40 kg, all is running smoothly like a warm knife through a pack of butter (dutch saying/proverb )
Take a test on 12v and see how it suits you. Be sure to have a quality stabilized 220-12v powersupply, we have two types in use, both from Voltcraft. You can find and buy them online here:

http://www.conrad-international.com/Fix ... 10310&Ctx={ver%2f7%2fver}{st%2f3eb%2fst}{cmd%2f0%2fcmd}{m%2fwebsale%2fm}{s%2fconrad-int%2fs}{l%2fint%2fl}{mi%2fSHOP_AREA_17452_2110310%2fmi}{pi%2f510161%2fpi}{sf%2f%3Cs1%3E12%20volt%3C%2fs1%3E%3Cs2%3E%24%241%3C%2fs2%3E%3Cs5%3E1%3C%2fs5%3E%3Cs11%3EVoltcraft%3C%2fs11%3E%2fsf}{fc%2fx%2ffc}{p1%2fba2cb60c553bbdac7c97d7c9e97f088c%2fp1}{md5%2f7ef972db5be3246b026c26a0e4f58c38%2fmd5}

and

http://www.conrad-international.com/Fix ... 10310&Ctx={ver%2f7%2fver}{st%2f3eb%2fst}{cmd%2f0%2fcmd}{m%2fwebsale%2fm}{s%2fconrad-int%2fs}{l%2fint%2fl}{mi%2fSHOP_AREA_17452_2110310%2fmi}{pi%2f510788%2fpi}{sf%2f%3Cs1%3E12%20volt%3C%2fs1%3E%3Cs2%3E%24%241%3C%2fs2%3E%3Cs5%3E1%3C%2fs5%3E%3Cs11%3EVoltcraft%3C%2fs11%3E%2fsf}{fc%2fx%2ffc}{p1%2fba2cb60c553bbdac7c97d7c9e97f088c%2fp1}{md5%2fb1fa5a6e94df0e7014469cc59ac6dc04%2fmd5}

Both deliver 12(13.8 in fact) volt @ 4 to 6 amp.

If the links does not work, go to http://www.conrad.com/ and search on power supplies and you'll find your way.

Succes, greetings,

Peter (administrator/moderator)

Thanks Peter, I have ordered an EA-PS 2010-05 for the Pulsar2. I will let you know how I get on.

Peter

Hi Peter

The Voltcraft EA-2010-05 has now arrived and does not work.....! It trips out as soon as I switch it on, so the G42 must be pulling more than 6A on startup.

I have a cheap 13.8v supply from Maplin that is rated at 5A continuous, 7A for 50% duty cycle and 9A maximum current. This one does work but has a bit more ripple than the Voltcraft supply, so I am using that.

I am surprised that the mount pulls over 6A on startup when it draws less than 1A in use, is this normal?

I have the tracking and stop currents set at 800mA. What are the settings you are using?

Best regards

Peter