Recent Posts

1

Test Equipment / Re: Tek 4 Series Hack

« Last post by skander36 on Today at 10:29:48 am »

Hello!
Anyone knows about progress in hacking MSO Tek series? I'm interested about MSO44 also.

2

Projects, Designs, and Technical Stuff / Re: Diodes Inc AP62300

« Last post by AnshumanFauzdar on Today at 10:26:58 am »

I am trying a similar design with 24v on input side, is it safe to connect EN to IN pin for 24v?

3

RF, Microwave, Ham Radio / Re: $10 OCXO board

« Last post by 807 on Today at 10:26:44 am »

Well, it was delivered way faster than said in the listing. I didn't test it until now.

It gave 10,000,003 Hz right from the start. Driving the trimpot to the limit, I'm getting 10,000,000 -10.000.001 Hz. Counter has accuracy of +/- 1 count +/- time base accuracy so pretty happy with it.

I think it probably woulnd't be worth the hassle to change any resistor so it could be adjusted exactly to 10 MHz

OCXO is CTI OSC5A2B02

Have you ever calibrated the internal timebase of your counter with a higher order reference? The spec for that counter is 1ppb, so could be up to 11Hz out at 10MHz.

I measured mine on a counter with a GPSDO external reference.

4

Beginners / Re: Inexpensive micropower buck-boost converter with wide input range?

« Last post by LinuxHata on Today at 10:22:01 am »

Unfortunately, no, I need non-inverted output.

5

Power/Renewable Energy/EV's / Re: Positioning of Solar Panels

« Last post by nctnico on Today at 10:20:15 am »

I have a feeling that the loop the panels make is too long. As a rule of thumb, the plus and minus should run along the panels in order to minimise the loop area.

6

Test Equipment / Re: Hantek DSO2000 Master Thread (DSO2C10 DSO2C15 DSO2D10 DSO2D15)

« Last post by unicornio on Today at 10:17:33 am »

hi, David,

I just wanted to publicly thank you for your work with this cheap oscilloscope...really the cheapest instrument I have ever bought in my life...:-)
It didn't work too badly with the firmware that came from the factory, but when I updated it with the firmware that Hantek has on its website, everything fell apart...it kept hanging...

With your latest firmware it's back to normal...

Thanks again

un abrazo desde gredos, españa!
Salud!

7

Projects, Designs, and Technical Stuff / Re: How to make a one-transistor bjt 2KHz amplifer work over 3.3 to 4.2 V Vout=1-V

« Last post by Salome2 on Today at 10:16:53 am »

Thanks PCB.Wiz, but rather than order the matched pair,  I will assume(with some testing using a soldering iron tip to heat the transistor pair to very warm) a superglued transistor pair for temperature comp is good enough for my simple requirement to  keep output capability of 1-V PP undistorted collector swing over room temperature operating range.

Thanks Magic, can you do a simulation on LTSPICE (or show me how) to verify this?

The very real problem is correct B-E bias voltage at Vbat=3.4V over temp range.

Vcc/21 

8

Projects, Designs, and Technical Stuff / Re: Relatively high voltage precision DAC amplification

« Last post by Laval on Today at 10:16:13 am »

You can, but not using the same circuit for the low voltages.

Yes, I'm thinking about having a different path for low voltage and HV. In fact, I'm thinking about developing the HV part in a modular way so that it can be added as an option. Of course, that requires the module to be prototyped and tested.

... used to individually test the resistors for TC ...

Like Conrad Hoffman said, I will keep current low at least at high voltage (0.5 mA at 1kV is 0.5 W, 1W if I go to 1 mA). Hopefully this will help mitigate TC. I read that VCR (voltage coefficient) particularly effect thick film resistors and that specialized HV film resistors use a different internal geometry to mitigate that effect. Does voltage effect wirewound resistors as well and as much ?

HV is something I don't know all that well. I have never worked with anything above 150 VDC and it scares the hell out of me. When I start prototyping with HV, I'll make sure to be very careful. I'm worried about the feedback loop, connecting 1K output to the input of a precision op amp, even with a divider looks scary to me.

Is this a one-off, or production?

Yes it is a one-off product. I don't intend to market this product. If I get a decent design, I will certainly make it open source but only if the result is good. I'm at a very early stage and perhaps I should have waited to have something to share before posting. I'm supposed to get my DAC today so I can start evaluating figures like noise and accuracy. Unfortunately, it comes with an ADR445 voltage reference which is probably not the best for my application. I'm thinking more about using an ADR1399 but that's a discussion for the Metrology forum (which have already been discussed quite a lot).

9

Beginners / Re: Lifting and tilting 0402 SMD LEDs by solder paste while soldering

« Last post by eleguy on Today at 10:14:37 am »

As someone already stated I also think you have pushed in too much paste.

10

Manufacturing & Assembly / Re: Which soldermask colour has best component visibility

« Last post by loki42 on Today at 10:14:06 am »

Is this for manual soldering or machine?  If it's for machine if it's you just use l test a few of each colour and see what your printer / aoi / spi has problems with. Green is usually the best.  White and black would be bad on my machines.