Monday, September 14, 2015

Dynamic Digital Tutors

Date: Wed, 30 May 2007 17:00:46 -0400   - Subject: 555 simulator


I just found and had a chance to play with the 555 simulator over the internet. As I do a lot of designing and use the 555 in many of my projects, this tester is a really handy tool.

Is there a way to get a copy of this simulator that will simply run on Windows? If not, how about running it through Internet Explorer?

I realize I could simply put a link to your site and use it that way, but I don't always have a connection to the internet. Basically, I would just like to use this little applet on my laptop on my bench at home.

Thanks for your help, and congratulations on such a cool program.

Mail from DN Canada

I am happy you found my gadgets fun to use. ,

555 Oscillator and Decade Counter -Red Button Powers LED Running Lights, Adjust R2, Move Mouse over the Images.

Astable Multivibrator with 555 - Red Button Powers, Move Mouse over objects to know.

Preset Digital BCD Counter - Move Mouse over the Images, Tool Tips will Tell All.

Dynamic Digital Tutors

In the links above, you will find a code to add to your webpage or blog. I have sent you a gmail invite get a gmail then use that login to open a account.

You ought to have a blog, these gadgets (code) can be added to your own blog, then you can refer it at your own pages. You can then share your learning with your friends too.

If you still want you use it offline let me know, i will make a zip and send it to use without internet. Have you tried using a Wireless LAN.

Wireless LAN - Wiki- A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum or ..

Then lastly ... check these freeware you can download for 555

555 Timer PRO provides an array of design wizards, circuit blocks and information panels that facilitate the use of the 555 timer. Component value calculations for the 555 take into account the supply voltage, timer fabrication (CMOS or Bipolar), and, where appropriate, load currents.
(use the freeware version)

555 Timer Project Design Software for Beginners and Experts

Let me know if you need anything more.


Hello again,

Thanks for your quick reply. As I don't have a website nor a blog, I was hoping that the 555 program could be just a stand-alone application. Is this possible?

Your program is really nice, so I hope it can run as a small program by itself.

Reply from DN

Here is a file that will work in your laptop without internet. Can you please verify if all the three work well. digital-tutor.chm - right click - save as - to a folder of your chose and then open it (removed)

Please check both online and laptop without internet. Your feedback will be useful to me so that i can correct or improve.


See the Complete - 555 Timer at EEMetric

Wednesday, September 09, 2015

Insulation Resistance Analyzer Required

Please quote for Insulation Resistance Analyzer DRT101

from AT 

delabs is a website for education of engineers and hobbyists . The photos and documents are products that i used to make years back. I do not manufacture now. The circuits and photos are to give ideas for youngsters and entrepreneurs.

Insulation Tester and Tera-Ohm Meter with Polarization Index
One of the Products i made and marketed in the Eighties.

Insulation Tester and Tera-Ohm Meter with Polarization Index


Monday, September 07, 2015

Polarized Capacitors and 555


This circuit of yours is EXACTLY what I was looking for. TOTALLY cool! However, I have a few questions about it...mostly because I'm a software guy. Astable 555 Timer Flasher

So please bear with me if these questions sound stupid...

1) I want a 50us on / 280 us off (3000 khz ish with at 15% duty cycle) circuit. THis means that Ct needs to be about 7000pf. Unfortunately, you can't get 7000pf caps polarized. Does Ct REALLY need to be polarized?

2) Also, what does a polarized capacitor do that an unpolarized one can't? Could I just stick a diode on it to make it polarized?

Polarized Capacitors and 555

3) THere's a bubble on pin 4 (the reset pin) on the 555. Does that mean I need an inverter? Would a 74HC04 do the trick, or is there an easier way to do that (I need the HC because I have 6v Vcc)

4) I just want the output signal...can I drop all the LED and battery stuff to the right without affecting the circuit?

Mail from GK

1) A cap being polarized is due to manufacturing. Only Electrolytic Caps including tantalum caps and others that are polarized give you high capacitance. If you do it with just a plastic, mica or paper separator (dielectric) then you get very low capacitance. So they have to wrap or coil many meters of two-metal-films and a insulator like plastic sandwiched to get upto 10uF or even more. These are non-polar and will become very big for say 100uF. Hence we have the electrolytic caps with high uF for the PCB real-estate they occupy.

UnPolarized are ideal and can be used anywhere. Use Polarized caps where the footprint area you need is less for a certain value of cap.

So you choose caps based on space, cost, AC-DC, purpose. Thumb-Rule 1uF and above only el-caps. Unless you need it in a AC circuit or high voltage like 1 Kilovolts where polyester caps are used. 7000pf or 7nF is available as ceramic, mica, plastic, paper. use what you get right now. Making 7nF el-caps was never required. 1uF and Above el-caps.

2) Being a polarized cap is an handicap. So you dont need to polarize a unpolarized cap, so just leave it alone, it is fine as it is.

3) The bubble says "I pin 4 of 555 have a inverter inside the 555".

4) You can drop the LEDs, but you have to power the circuit with a batt or mains-DC-9V-adapter.


Thanks for the response! So I don't need a 74x04 chip to go into the reset pin? Cool. I'll stick to the non-polarized cap and and a direct input into the 555 pin 4. The board I'm using is powered by 6v, I hope this will do the trick, don't want to go the rectifier route.

Reply from GK

"When you build projects Software and Hardware, design products and services that are useful to society" - Solderman 1709