IMPORTANT Skywatcher Synguider Autoguider

[FLO]

Have just received the following from Skywatcher's UK importer:

IMPORTANT NOTICE REGARDING SKY-WATCHER SYNGUIDER

Please note there is a printing error in the instruction manual concerning the power supply requirement of the Synguider.

Firstly, please note it is recommended to use the battery pack supplied.

The operating voltage of the SynGuider is DC 6V-12V (Lower voltage recommended).

Some cheap PSU's rated at 12volts do actually give out a higher voltage and its the voltage that will damage the unit. Therefore a good quality switchable Power supply is needed to select a lower voltage.

HTH,

Steve

[Psychobilly]

Just run them from a lower voltage supply... don't run them from a 13.8V one that you would typically find in the obs for running the other kit...

6.5V works a treat for me... the current rating bit is a bit of a red herring really...

Peter...

[wayne weedon]

Just run them from a lower volatge supply... don't run them from a 13.8V one that you would typically find in the obs for running the other kit...

6.5V works a treat for me... the current rating bit is a bit of a red herring really...

Peter...

I thought that too. A circuit will draw just what it requires even if you have a 100 Amp PSU! Unless theres a fault with the circuit of course.

Wayne...

[SteveL]

the current rating bit is a bit of a red herring really...

Thats confusing isnt it.... Voltage is supplied, but current is drawn. You can supply too much voltage to something, but you cant supply too much current, as it is the unit itself that determines how much current it draws.

A bit on odd not8ice to be honest...

[Psychobilly]

The Original manual says 6-14V DC so I guess the error they are really correcting is that the max operating voltage specified is too high...

I guess they might have had a few problems with them being run at 13.8V maybe...

Page 3 of the original manual (page 4 of this PDF)

http://www.graigolaobservatory.org.uk/Synguider/SynGuider%20Manual_v1.pdf

Peter...

[steppenwolf]

Well that's the weirdest notice isn't it! As has already been discussed, current is 'drawn' on demand not 'supplied' so that is a nonsense. With the voltage, it either IS suitable for 12v operation or it isn't! The manual actually quotes 6v to 14v so I guess they were thinking 13.8v nominal and they may well have got that wrong as many devices are 12v and that does NOT mean 13.8V as per the alternator output in a car charging system!!

However, a lower voltage may be 'preferred' to ensure less heat build up from the dissipation required from what I suspect is a voltage regulator supplying a 5v rail to the device.

[barkis]

This device is obviously too sensitive to have a spread of 8 volts.

Let's face it, if 6 volts will drive the camera, why have an upper limit of 14v. A number of electronic devices would fail if a voltage over 100% higher was applied. If it didn't have a V Regulator protection.

------------

Many people do not read a Manual in depth, and merely look for the relevant bits, like power supply. All they will see, is the range 6v to 14v, and if they have a PS supplying 13.8v, as I'm sure many will, they will instinctively use it.

Ron.

[FLO]

Your comments haven't gone unnoticed, this just in:

Regarding the Synguider current rating - actually that is misleading and can be disregarded. The main point is some cheap PSU's rated at 12volts do actually give out a higher voltage and its the voltage that will damage the unit. Therefore a switchable Power supply is needed to select a lower voltage.

I shall edit the original announcement.

Isn't the internet wonderful

[SteveL]

yay us!

[steppenwolf]

[Earl]

It would make sense that manufactures would be "Legally Obliged" to supply the exact power supply that an item requires.

And provide Replacments at a realistic price.

Of course common sense does not always win.

[glowjet]

I presume all the above information relates to 240 volt power supply units, to run the unit in the field, with a large dry cell or heavy duty 85 amp/h leisure battery which exceeds 12 volts, then is it going to be advisable to introduce a small voltage regulator unit into the circuit, like those sold by Maplin, the down side is, it is going to increase current consumption.

[glowjet]

Thanks Peter I see you answered this same question under EQ Help on the 11 Aug.

[Psychobilly]

No worries it popped up in a few different threads...

[FLO]

HitecAstro have introduced a power supply for the Skywatcher Synguider.

HTH

[gcraib]

Well that's the weirdest notice isn't it! As has already been discussed, current is 'drawn' on demand not 'supplied' so that is a nonsense. With the voltage, it either IS suitable for 12v operation or it isn't! The manual actually quotes 6v to 14v so I guess they were thinking 13.8v nominal and they may well have got that wrong as many devices are 12v and that does NOT mean 13.8V as per the alternator output in a car charging system!!

However, a lower voltage may be 'preferred' to ensure less heat build up from the dissipation required from what I suspect is a voltage regulator supplying a 5v rail to the device.

Actually a lower voltage will give create more heat as the current drawn will be higher. ('heat power'- P=I^2R)

Its the insulation of components inside that may not withstand a higher voltage. But if they are saying its rated 6-12V then 6-12V should be fine otherwise its faulty. If there is an issue with 14V or even 15-20V I'd say it has poor insualtion and would avoid.

[Psychobilly]

Sorry your wrong...

The Synguider has a linear regulator inside it the internals run from a much lower DC voltage so the higher the input supply voltage the greater the voltage drop across the regulator , the more power that gets dissipated and the unit runs hotter...

With a linear regulator system the current drawn will not depend on the supply voltage but the current drawn on the load (output) side of the regulator...

Peter...