I really need your point of view

[ikalogic]

I am writing tutorials on my website, that you can find at this page:

**broken link removed**

Many of you here may have seen it before, if not, you may take a quick look

I really need to know if it is woth it, i mean does anyone find it usefull?
Is the material well presented so that people can benifit from it?
Is it worth spending long night of works?
Should i continue with this or is it a waste of time?

 

[Hero999]

Good but I'd suggest using PNP transistors for switching the high side on the h-bridge. Emitter followers don't saturate properly and there's always a 0.7V+Saturation voltage loss.
**broken link removed**

 

[Styx]

following on from Hero999 comment, the base-drive's have a source potential of 12V, the same potential as the DC-link, thus the H-bridge BJT's will def not saturate since there will not be enough potential difference (between emitter and the base) to drive current into the base to turn them on (use PNP's since down at 12V)


Also just incase you plan to PWM this
the base-drive will be slow. You use a BJT to sink current out of the H-bridge BJT's (so they will have fast-turn-off) but you have 10k pull-up to then drive current into the base of the H-bridge BJT's

 

[ikalogic]

Also just incase you plan to PWM this
the base-drive will be slow. You use a BJT to sink current out of the H-bridge BJT's (so they will have fast-turn-off) but you have 10k pull-up to then drive current into the base of the H-bridge BJT's

hmm.. i'll need some more convincing on this point.. about the fast/slow response.. i mean this may be true for MOSFETS or IGBT where the induced channel have to be narowed with a negative voltage...

i am not as experienced as you, nor i am questioning what you said.. i am just interrested in some more details. thx

 

[Hero999]

Your new circuit still has issues.

The right PNP transistor (Q5) will be destroyed when Q3 turns on because there is nothing to limit the base current.

There are no diodes to protect the transistors from the back-emf genterated by the motor.

Have you considered using MOSFETs as an alternative to bjts?

 

[Roff]

In your DAC, the output resistance of the R-2R ladder is R. You can connect a resistor from the output to GND to attenuate the signal. A resistor of value R will, in your example, reduce the output swing to be zero to 2.5V.
Keep in mind that, if you want the output to be monotonic, you should use 0.1% resistors for an 8 bit DAC, because the LSB is 0.4% of full scale. Also, the output resistance of each logic stage adds to the value of R.
I might use 1Meg and 499k, 0.1%. You can also buy R-2R networks with guaranteed +/- 1/2 LSB accuracy.
I realize that you don't always need this kind of accuracy, but I think it is good to know, so you don't get any surprises.

 

[Sig239]

Hello Ikalogic, your site looks great. The layout is very visually appealing and the graphics are very nice. However, I did notice a couple of things that could use some attention. On the page you linked to, all but the first paragraph had some sort of error. Perhaps another set of eyes in the editing department could help.

1. N.b.: Fell free to use..... should be: Feel free
2. and small size H-bridge module suitable for most roboics applications... Should be sized....and robotics
3. taking you step by step though all the...should be through
4. NOTE: this is a introduction to ferquency meters...Should be AN introduction and frequency
5. remarkable range, specially in indoor..Should be especially
6. a problem encourted by many...own DAC, and propses a very...Should be encountered and proposes
7. Built to experiment the behavior....experiment WITH the behavior

I noticed this on the projects pages too. Once these minor quirks are ironed out you will have a top notch site on your hands. Your website design work really shines and I like your projects. I will bookmark it!