Joule Thief

[resonanceman]

To all who look for a tool to measure Joule Thieves:

I got the DSO-2100 USB PC USB Digital Storage Oscilloscopes which is not sold any more (it is about 4 years old) and it helps me a lot. It would be very boring without it.

The newer model DSO-5200 (resonanceman posted it) is a very good choice today, or that one: http://www.hantek.com.cn/english/produces.asp (DSO 2150). Hantek manufactures these oscilloscopes in China and they are sold by various distributors.

Attached two scope shots I did today with my DSO 2100. The point is, that one can see the  most complicated wave forms very nicely.

It is very helpfull to buy a x100 probe (in addition to a x1 and x10 probe), which I use to measure signals up to 3500 Volts.

On the attached scope shots you see a measurement over the secondary of a joule thief that gives about 600 Volts (air coil).

It is quite easy to use my DSO 2100, although one can get missleading results as a beginner. The probes I got prevented all disasters because they have a high impedance (resistance). Sometimes I do not understand the measured result because I do not understand the interaction of the scope probe with the circuit, specially when I measure high frequency signals. Sometimes the circuit stops working when I attache the scope probe (also an interaction of the probe with the circuit). But I am getting better at it.

I like very much that the scope on the USB port of my PC allows storage of the measurements as images which I can recall later. A drawback is that one needs a PC or Laptop to use the scope.

Best would be a stand alone DSO which can also be connected to a PC (but that costs several thousand Euros).

Greetings, Conrad

Thanks for the info  Conrad

It is good to know that a X100 probe is available  for the 5200

gary

[freepow]

Hello all,  great scope shots !  But if one wants mobility without a PC and limited in funds, then maby consider the portable UT81B at $198.99 US +free postage, Can measure to 1000 VDC with scope !
What does everyone think ?

[resonanceman]

Hello all,  great scope shots !  But if one wants mobility without a PC and limited in funds, then maby consider the portable UT81B at $198.99 US +free postage, Can measure to 1000 VDC with scope !
What does everyone think ?

Freepow

That looks like a great deal.

I considered it when you  first posted  about it.

I don't remember seeing  a scope  for a lower price.

I am  going for  a USB scope  because I want  to be able to  have a big  image if the waveform.
I also like  being able to do a scope shot  with just a few clicks.


ANother thing  that is important to me.  I want 2 channels so I can do things like watch the  primarys and secondary at the same time

I am  also thinking that  a USB scope should be able to be used like a data logger.......

gary

[Pirate88179]

Also, if used on a laptop it is just as portable to use in the filed.

Bill

[conradelektro]

@ all interested in a USB Digital Storage Oscilloscope (DSO):

The discussion got me interested in doing a quick on-line search for USB DSOs.

I found this British firm:

http://www.picotech.com/oscilloscope-specifications.html

http://www.picotech.com/computer-oscilloscope.html  ( PicoScope 3200,  £399.00, $658.35, â,¬466.83 )

The PicoScope 3200 is a bit expensive, but its specifications look good. Farnell sells it, so chances are high that it works.


@ Gary (resonanceman) and all who want 2 channels on a scope:

On my DSO-2100 the "ground" of the two channels is the same, which limits the simultaneous use of the two channels. Many inexpensive USB DSOs with two channels will be constructed in a similar way.

If the two signals I want to measure have the same "ground", I can see them together in different colours (which is very nice); if not, I will connect something in my circuit which should not be connected or one of the measurements will be meaningless.

The secondary coil in a Joule Thief type circuit behaves differently or fails when you tie it down to the same "ground" (battery pole -) as the Joule Thief circuit. Meaning, I can not measure the signal on the secondary together e.g. with the signal over the collector - emitter with my DSO-2100.

Two channels are good but you have to think before connecting two probes to your circuit.


@ all who like hand held scopes:

The inexpensive hand held scopes have a very limited frequency range (5 to 10 MHz) and a very limited resolution (on screen and in the memory).

The very good products from FLUKE are expensive:
http://us.fluke.com/fluke/usen/products/categoryoscill?trck=scopemeter

Greetings, Conrad