Search found 106 matches

by ecerfoglio
Fri Jun 30, 2006 6:05 am
Forum: General Discussion
Topic: 555/decade counter 7 seg display help
Replies: 20
Views: 4637

it says that the circuit accepts any TTL compatible logic signal so being the amatuer that i am i must ask. My board is using a standard 555cn timer as the osc. for the decade counter 4017be.. Both a 555 and the 4000 series CMOS may be used with a wide range of supply voltages (from 3 V to 15 V (or...
by ecerfoglio
Wed Jun 21, 2006 5:41 am
Forum: General Discussion
Topic: Note on spam topics
Replies: 13
Views: 2647

With the "old" forum software we had a "REPORT" button to alert the administrators.

Can this be implemented in the new one so we can give the alarm when we find a spam post?
by ecerfoglio
Thu Jun 15, 2006 8:19 am
Forum: General Discussion
Topic: Hook xformer for 120 VAC
Replies: 10
Views: 1685

One ** SAFE ** way to be shure of the polarity of the two primary windings: 1: With an ohmeter, identify the primary and the secondary pins. Identify the two pairs of primary pins (1&2, 4&5). Leave the secondary open 2: Connect one pin of each pair (ie 1 and 4) together to one side of the 110 V line...
by ecerfoglio
Fri Jun 09, 2006 11:52 am
Forum: General Discussion
Topic: Changing a bulb?
Replies: 15
Views: 4535

not enough traffic
I remember some topics :sad: with more than ** 15 pages :shock: **.....
by ecerfoglio
Tue Jun 06, 2006 3:28 pm
Forum: General Discussion
Topic: Error free (or very close) optical tach output
Replies: 6
Views: 1129

Philba's advices address the "electronic" part of the issue: - bypass all ICs - make sure you have clean power - keep the tach signal away from other signals - low pass filter the tach signal for something like a 1khz 3db point - schmitt triggers Once you have taken care of that "electronic" part, l...
by ecerfoglio
Wed May 31, 2006 10:21 am
Forum: General Discussion
Topic: RC Snubber Circuit Basics
Replies: 1
Views: 749

No, in your application it doesn't matter if you connect the R to the data line and the C to ground or the C to the data line and the R to ground. The order may be important in some cases with very high voltages (ie: the capacitor's case should be grounded) or in some radio frecuency circuits (where...
by ecerfoglio
Wed May 24, 2006 6:12 am
Forum: General Discussion
Topic: pos 12 volts to split 5 volts supply?
Replies: 18
Views: 4289

Dacflyer's original post: from a 12 volt DC single supply ..... its no problem if i use batterys, but i want to use a old wal-wart ... If you don´t need too much current and you have an AC wall wart you may try something like this: One wire from the wall wart goes to ground. The other wire goes to ...
by ecerfoglio
Tue May 16, 2006 3:32 pm
Forum: General Discussion
Topic: ID this RFID
Replies: 10
Views: 1769

Theese "cheap" tags may be only a tuned circuit: a printed coil and a capacitor. The sensors are BIG coils that emit RF. When you pass between them, the tag absorbs power in that especific frecuency and trips the alarm. When you buy the item that has the tag, they "kill" the tag in a special "deacti...
by ecerfoglio
Tue Apr 25, 2006 10:33 am
Forum: General Discussion
Topic: Similar to a solar cell...
Replies: 16
Views: 5420

To extract energy from a high intensity radio field you only need an antena. If you want to obtain DC just rectify the antena's output with a diode and add a filter capacitor. You can use a schottky diode to lower its voltage drop and power loss. With "faint radiowaves from broadcasting" you can use...
by ecerfoglio
Wed Apr 19, 2006 5:48 am
Forum: General Discussion
Topic: This one for the Nuts, not for the Volts...
Replies: 22
Views: 5021

To work as a refrigerator, the compressor's output should be hot, and at a higher pressure than it´s input. In "ideal" conditions, you should start the compressor before you start the expander so the pressure has time to build up. With real machines (air leaks, friction, etc) the compressor should ...
by ecerfoglio
Mon Apr 17, 2006 7:35 am
Forum: General Discussion
Topic: avatars?
Replies: 15
Views: 3509

[quote] EDD posted:
As per the “resistance wireâ€
by ecerfoglio
Thu Apr 06, 2006 6:10 am
Forum: General Discussion
Topic: 90 Watt LED Driver - Need a bit of help here :)
Replies: 57
Views: 11437

The most efficient way to operate the diodes would probably be a series string of 18 fed with a boost type of converter, as you suggested. The reason that I did not suggest this, and probably the reason that dyarker didn't also, is that this would probably require the design of custom magnetic part...
by ecerfoglio
Tue Apr 04, 2006 10:35 am
Forum: General Discussion
Topic: Instrumentation Amp issues
Replies: 11
Views: 4320

Re: Instrumentation Amp issues

For a project im working on i am using strain 350Ohm strain gauges in a bridge configuration to measure the pressure wave created in ballistic gelatin. I need an instrumentation amp capable of doing 0-500Khz as far as bandwidth is concerned. I have tried my hand at building a classic 3 op amp instr...
by ecerfoglio
Fri Feb 17, 2006 12:43 pm
Forum: General Discussion
Topic: Convert 120 VAC to 5 pulsating DC.
Replies: 14
Views: 2359

Re: Convert 120 VAC to 5 pulsating DC.

If you already use a transformer, rectifier, filter (and regulator?) to power your circuit, the "pulse" supply can be just an aditional diode (or two for 120 Hz). It would be better if the main suply is either half wave or has a center tapped transformer, as in that case you have one side of the tra...
by ecerfoglio
Fri Feb 17, 2006 6:37 am
Forum: General Discussion
Topic: hobbist where did we all go
Replies: 10
Views: 1835

Re: hobbist where did we all go

The valve generation probably said the same thing about transistors,... When my father (he is 73 years old) learned his electronics there where only vales, then he learned "solid state" (transistors), analog IC's (like op amps), digital IC's (TTL and CMOS)...And he now uses microprocessors in his d...