Ultrasonic oscillation is basically a tone above your hearing. You can't directly hear it, but you can hear the effects it has. It can make audio circuits sem like they have all kinds of problems.
You wouldn't believe what problems can exist while equipment still "sounds good". There is no substitution for having a look. Saves a lot of time and discussion.
-Chris
You wouldn't believe what problems can exist while equipment still "sounds good". There is no substitution for having a look. Saves a lot of time and discussion.
-Chris
Thanks for suggestions.
Thanks to everyone who contributed I learned a lot from this thread! I have since sent the amp as it to a friend and so far there are no complaints. I guess there wouldn't be since its free LOL.
I think I need a tone generator or possibly output of sound from computer to use with the oscilloscope to measure output. Even though its not that great, the kit cost like £25!
Again Thanks guys but I will leave the more complicated stuff until I get better at what i'm going!
Hi dj_holmes,
What kit did you get?
By all means, use the sound card and some software. Better than nothing and higher quality than a function generator.
When you figure things out, remember that you can't get anywhere while fighting with your instruments. As a young fella, I bought a Fluke 8200 (I think, nixie tubes). It was a very expensive meter, but I scored it used for not much. More meter than I needed, but I learned a lot with it - and the maths worked out properly for circuits. This meter also had the following options:
* ohms
* millivolts
* AC voltage measurement
I didn't know they were options, but they were expensive, full length cards. Later I bought two more striped down units. DC volts only. Still have them.
Whatever you buy, buy instruments of reasonable quality. Be realistic about how accurate you think they are.
-Chris
What kit did you get?
By all means, use the sound card and some software. Better than nothing and higher quality than a function generator.
When you figure things out, remember that you can't get anywhere while fighting with your instruments. As a young fella, I bought a Fluke 8200 (I think, nixie tubes). It was a very expensive meter, but I scored it used for not much. More meter than I needed, but I learned a lot with it - and the maths worked out properly for circuits. This meter also had the following options:
* ohms
* millivolts
* AC voltage measurement
I didn't know they were options, but they were expensive, full length cards. Later I bought two more striped down units. DC volts only. Still have them.
Whatever you buy, buy instruments of reasonable quality. Be realistic about how accurate you think they are.
-Chris
I purchased this kit:
JYE Tech DSO138
Haven't used it for anything. Did play with it a few times but definitely a project for when there's plenty of free time!
Hi dj_holmes,
I have reservations about that kit. You should have a 1 MHz sampling rate and that's really not quite there. The reason for this is that most of the time an amplifier misbehaves, it does so about 100 KHz. Your kit stops at 100KHz, possibly lower. In addition it is likely you may run into aliasing problems. This occurs when a signal above the 1/2 sampling rate gets into the system. It is "reflected" back as if it is within the band of your scope. So for example, a 108 KHz signal would look like a 92 KHz signal to you.
It is useful for getting an idea of how things work, and as long as whatever it is you're working on is playing nice, you will see a signal (with little detail). Good for experiments but not really intended for the real world.
Go ahead and use it with these things in mind.
-Chris
I have reservations about that kit. You should have a 1 MHz sampling rate and that's really not quite there. The reason for this is that most of the time an amplifier misbehaves, it does so about 100 KHz. Your kit stops at 100KHz, possibly lower. In addition it is likely you may run into aliasing problems. This occurs when a signal above the 1/2 sampling rate gets into the system. It is "reflected" back as if it is within the band of your scope. So for example, a 108 KHz signal would look like a 92 KHz signal to you.
It is useful for getting an idea of how things work, and as long as whatever it is you're working on is playing nice, you will see a signal (with little detail). Good for experiments but not really intended for the real world.
Go ahead and use it with these things in mind.
-Chris
Taking a look at the JYE kit (I wasn't aware of them before) the DSO112A looks like it may be ba better bet in terms of bandwidth for hf problems - although check the resolution figures. More tha 2xcost of the kit in question -
and it appears to come ready built - but still on the cheap side for scope function.
That's certainly true. Although reliability and servicing can become a real issue with older kit depending where you buy it dealer / private / ex-hire.
Personally I have an old Tektronix 2215 and from work access to a GWInstek - I'd not heard of the brand previously - 4 channel DSO.
tbh much of the time I prefer to hook up the Tektronix as it feels like a probe 'hard wired' to the CRT rather than playing around with Modes / Averages etc on the DSO although the recording and measurement functions are very useful in some instances.
But the Tektronix has a mechanical problem with one of the input BNCs (as well as channel calibrations being significantly out on one channel) and I know that'll be a right pain to fix in terms of time and/or cash.
I originally bought in the Tektronix for a past employer and late 90s and it was from a used dealer then !
But you can't guarantee availability of these things and the higher spec JYE model I pointed too looked like it might be of interest. As you say the lower spec used by the OP will 'run out of steam' for serious work.
One thing I do like about the smaller units is that they are smaller (obvs
It can be awkward to set up a big (deep) scope like mine depending on where you need to probe.
Hi rmaudio,
The other issue is that the input isn't that well protected in that kit, whereas the older oscilloscopes are difficult to damage doing normal work with them. Obviously measuring the anode voltage on a CRT will usually bake whatever has been connected unless it was designed specifically for very high voltage. With a 5V peak maximum input voltage, the kit is vulnerable to a slip of the switch on the X10 probe (epoxy probes into the X10 position!) and even a moderate powered amplifier may run beyond 50 VDC rails. That is above the spec of this DSO. So buying a X100 probe might be in order.
-Chris
The other issue is that the input isn't that well protected in that kit, whereas the older oscilloscopes are difficult to damage doing normal work with them. Obviously measuring the anode voltage on a CRT will usually bake whatever has been connected unless it was designed specifically for very high voltage. With a 5V peak maximum input voltage, the kit is vulnerable to a slip of the switch on the X10 probe (epoxy probes into the X10 position!) and even a moderate powered amplifier may run beyond 50 VDC rails. That is above the spec of this DSO. So buying a X100 probe might be in order.
-Chris
Hello Anatech
Oh - I hadn't checked the input ratings - yes that is a vulnerability.
Just checked and My Tektronix is 400Vpk and the DSO 300Vpk at the BNC.
I recommended non switchable probes fixed at x10 and yes x100 also.
Apart from the ratings I usually find the first thing to go iffy on a probe is that switch.
Oh - I hadn't checked the input ratings - yes that is a vulnerability.
Just checked and My Tektronix is 400Vpk and the DSO 300Vpk at the BNC.
I recommended non switchable probes fixed at x10 and yes x100 also.
Apart from the ratings I usually find the first thing to go iffy on a probe is that switch.
Thanks for info guys...
some one posted a link to another thread that I think I will start there first. Its for online learning..
Circuit analysis | Electrical engineering | Science |
Khan Academy
I think I will start there before buying/ experimenting seriously with a scope!
some one posted a link to another thread that I think I will start there first. Its for online learning..
Circuit analysis | Electrical engineering | Science |
Khan Academy
I think I will start there before buying/ experimenting seriously with a scope!
Not sure if this is the best thread for this but I have attached a schematic for an NE5534 preamplifier which contains four 100 pF ceramic disc capacitors.
I was wondering if the 100 pF ceramic discs across the feedback resistors are too big. Perhaps I should reduce them or omit them?
Asking for suggestions before going the alternative route of downloading LTSpice.
I was wondering if the 100 pF ceramic discs across the feedback resistors are too big. Perhaps I should reduce them or omit them?
Asking for suggestions before going the alternative route of downloading LTSpice.
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