Is this a good first scope? - Page 1
Forum section: electronics / general

author: Mint.
author_rank: Frequent Contributor
timestamp: April 06, 2012, 05:39:23 am
content: I've got a friend who became interested in electronics recently, spotted a good deal on this scope. My question is whenever it is worth it and should he buy it?http://www.ebay.com.au/itm/50Mhz-BWD-CRO-Oscilloscope-Scope-50-Mhz-/200737226808?pt=AU_B_I_Electrical_Test_Equipment&hash=item2ebcdf0038#ht_500wt_1413

author: saturation
author_rank: Super Contributor
timestamp: April 06, 2012, 03:26:59 pm
content: I think it is because its only for pickup, and from a University. BWD was an Australian brand. I presume you can test it before you pay for it. I would test it thoroughly since buyer will be there in person, and find its manuals to read about it to know how to test all its key functions.

author: T4P
author_rank: Super Contributor
timestamp: April 06, 2012, 05:59:35 pm
content: Well it is worth it as an australian brand , it looks great in any lab , with that huge front end .Still within the 50-100$ mark .Don't mark my commentary though .

author: nctnico
author_rank: Super Contributor
timestamp: April 07, 2012, 06:04:09 pm
content: The big question is whether all the switches and pots are still working OK. I can't judge the age from here but if its over 20 years old I wouldn't buy it. Its not so easy to test an oscilloscope quickly. You'd need to apply a square wave at different frequencies / amplitudes and know exactly what to expect. BTW there are so many nice entry level digital scopes nowadays which offer so much more like making snapshots, frequency analyses, long memory, etc that its hard to beat the bang-for-your-buck.

author: Unknown
author_rank: Unknown
timestamp: April 07, 2012, 06:32:30 pm
content: Most analog scopes you find will be over twenty years old, especially the affordable ones.I agree that a low-end DSO offers more bang for most (digital) applications, but I'm not so sure about the bang per buck. Analog scopes can be found for under $50, sometimes even for less. Even a 50 MHz Rigol scope will cost $300+. Is it really worth six times more to all users?

author: saturation
author_rank: Super Contributor
timestamp: April 08, 2012, 01:14:17 pm
content: A fast simple way is a 10 MHz square wave from a good source or a fast pulse generator, the former is likely easier to find; its common in good function generators. Let the scope and source warm up for 30+ minutes or so, if possible. Call the seller and tell him to warm it up for you to save time before you get there.Since the rising edge represent ~ 5x the fundamental, to look 'square' means it can easily do 50 MHz. If the square wave train looks symmetrical, the horizontal time base and vert amps are ok. Quickly adjust them to insure symmetry throughout the range.At most expect 'scratchy' or noisy pots when you turn them, a spritz of Deoxit cleaner [ or your country's equivalent] is all it may need.P.S. Make sure you use good probes!

author: nctnico
author_rank: Super Contributor
timestamp: April 08, 2012, 08:45:38 pm
content: A 10MHz square wave won't cut it. I've come across scopes which will show such a signal perfectly but fail at LF signals. Many scope input amplifiers consist of an amplifier for DC (and LF) and an amplifier for HF in parallel. And there are the input dividers.I strongly advise against using 'contact repair spray'. It helps for a day or two but in the long run it ruins equipment because the acids it contains will eat away copper and other metals. If a switch or pot is bad, the only real solution is replacing it. The reason its bad is because the contact layer is gone. A contact usually consists of a stiff base material which is plated with another metal which has good conducting properties and doesn't corrode quick. If that layer gets worn of the contact just won't work.