Forums

555 timer

Started by George Herold December 23, 2011
Hey, I think I=92ve got a use for a few dual 555 timers.
(First time in ~20 years)
I want to make some signal sources with a max freq. of maybe 100kHz.
(I figure I=92ll heavily RC filter the output)
I was going to order the CMOS version (TS556).  Is there any reason to
use the TTL one?  (NE556)  The minuscule cost difference makes no
difference to me.

Thanks,
George H.
George Herold wrote:
> Hey, I think I�ve got a use for a few dual 555 timers. > (First time in ~20 years) > I want to make some signal sources with a max freq. of maybe 100kHz. > (I figure I�ll heavily RC filter the output) > I was going to order the CMOS version (TS556). Is there any reason to > use the TTL one? (NE556) The minuscule cost difference makes no > difference to me. >
Can't comment, have never used it. My signal sources are generally 74HC14 or CD40106. You get six per package, dirt cheap. -- Regards, Joerg http://www.analogconsultants.com/
On Fri, 23 Dec 2011 10:55:43 -0800 (PST), the renowned George Herold
<gherold@teachspin.com> wrote:

>Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. >(First time in ~20 years) >I want to make some signal sources with a max freq. of maybe 100kHz. >(I figure I&#2013266066;ll heavily RC filter the output) >I was going to order the CMOS version (TS556). Is there any reason to >use the TTL one? (NE556) The minuscule cost difference makes no >difference to me. > >Thanks, >George H.
The drive current is a bit higher for the bipolar version, some of the CMOS types won't handle as much supply voltage. AFAIR, everything else is better on the CMOS- 100kHZ is getting to the limit for the bipolar type, but some of the CMOS ones will do MHz. With CMOS, swing is to the rails, no big spikes of current, no bias current to speak of. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Fri, 23 Dec 2011 14:42:08 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Fri, 23 Dec 2011 10:55:43 -0800 (PST), the renowned George Herold ><gherold@teachspin.com> wrote: > >>Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. >>(First time in ~20 years) >>I want to make some signal sources with a max freq. of maybe 100kHz. >>(I figure I&#2013266066;ll heavily RC filter the output) >>I was going to order the CMOS version (TS556). Is there any reason to >>use the TTL one? (NE556) The minuscule cost difference makes no >>difference to me. >> >>Thanks, >>George H. > >The drive current is a bit higher for the bipolar version, some of the >CMOS types won't handle as much supply voltage. > >AFAIR, everything else is better on the CMOS- 100kHZ is getting to the >limit for the bipolar type, but some of the CMOS ones will do MHz. >With CMOS, swing is to the rails, no big spikes of current, no bias >current to speak of. > > >Best regards, >Spehro Pefhany
Seconded. I don't use bipolars anymore at all. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Annoy a Liberal... Suggest That They Use Their Own Money to Fund a Company
On a sunny day (Fri, 23 Dec 2011 11:29:08 -0800) it happened Joerg
<invalid@invalid.invalid> wrote in <9lk34cF3npU1@mid.individual.net>:

>George Herold wrote: >> Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. >> (First time in ~20 years) >> I want to make some signal sources with a max freq. of maybe 100kHz. >> (I figure I&#2013266066;ll heavily RC filter the output) >> I was going to order the CMOS version (TS556). Is there any reason to >> use the TTL one? (NE556) The minuscule cost difference makes no >> difference to me. >> > >Can't comment, have never used it. My signal sources are generally >74HC14 or CD40106. You get six per package, dirt cheap. > >-- >Regards, Joerg > >http://www.analogconsultants.com/
555 is frequency stable versus supply voltage, that is its big plus. I use 4046 because it has a VCO frequency control DC input.
"George Herold" <gherold@teachspin.com> wrote in message 
news:b6317330-1cd8-4af0-a182-19716a2daaa0@j10g2000vbe.googlegroups.com...
> Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. > (First time in ~20 years) > I want to make some signal sources with a max freq. of maybe 100kHz. > (I figure I&#2013266066;ll heavily RC filter the output) > I was going to order the CMOS version (TS556). Is there any reason to > use the TTL one? (NE556) The minuscule cost difference makes no > difference to me.
I had used one of the cmos 555's a few years ago to drive a charge pump. Had previously used a bipolar unit and found the cmos just didn't have enough output drive for the task. Was easier to go back to bipolar rather than adding a buffer. Then it worked. I liked using the output rather than the discharge pin to discharge the timing capacitor to get a near 50% duty cycle. Single resistor from pin 3 to pins 2 and 6 and the usual capacitor from pin 6 to ground.
On Fri, 23 Dec 2011 20:12:25 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>On a sunny day (Fri, 23 Dec 2011 11:29:08 -0800) it happened Joerg ><invalid@invalid.invalid> wrote in <9lk34cF3npU1@mid.individual.net>: > >>George Herold wrote: >>> Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. >>> (First time in ~20 years) >>> I want to make some signal sources with a max freq. of maybe 100kHz. >>> (I figure I&#2013266066;ll heavily RC filter the output) >>> I was going to order the CMOS version (TS556). Is there any reason to >>> use the TTL one? (NE556) The minuscule cost difference makes no >>> difference to me. >>> >> >>Can't comment, have never used it. My signal sources are generally >>74HC14 or CD40106. You get six per package, dirt cheap. >> >>-- >>Regards, Joerg >> >>http://www.analogconsultants.com/ > >555 is frequency stable versus supply voltage, that is its big plus.
--- Only 1%/V at Vcc = 5V, but it tempco is 50ppm at Vcc = 5V ---
>I use 4046 because it has a VCO frequency control DC input.
--- 555 does too, but it's nowhere near as nice as the 4046's -- JF
"George Herold" <gherold@teachspin.com> wrote in message 
news:b6317330-1cd8-4af0-a182-19716a2daaa0@j10g2000vbe.googlegroups.com...
Hey, I think I&#2013266066;ve got a use for a few dual 555 timers.
(First time in ~20 years)
I want to make some signal sources with a max freq. of maybe 100kHz.
(I figure I&#2013266066;ll heavily RC filter the output)
I was going to order the CMOS version (TS556).  Is there any reason to
use the TTL one?  (NE556)  The minuscule cost difference makes no
difference to me.

Thanks,
George H.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

The bipolar 555/556 gives up the ghost at around 200kHz, years ago I kit 
built a TV pattern generator with 555 sync generators - the 15.625kHz line 
timebase 555 proved impossible to calibrate, it was pretty flaky and 
wouldn't stay set.

The bipolar 555 won't be any good as a stable frequency generator at 100kHz, 
the CMOS version is claimed to be good upto about 2MHz but has rather 
limited O/P drive capability. 


On Fri, 23 Dec 2011 14:38:31 -0600, John Fields
<jfields@austininstruments.com> wrote:

>On Fri, 23 Dec 2011 20:12:25 GMT, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >>On a sunny day (Fri, 23 Dec 2011 11:29:08 -0800) it happened Joerg >><invalid@invalid.invalid> wrote in <9lk34cF3npU1@mid.individual.net>: >> >>>George Herold wrote: >>>> Hey, I think I&#2013266066;ve got a use for a few dual 555 timers. >>>> (First time in ~20 years) >>>> I want to make some signal sources with a max freq. of maybe 100kHz. >>>> (I figure I&#2013266066;ll heavily RC filter the output) >>>> I was going to order the CMOS version (TS556). Is there any reason to >>>> use the TTL one? (NE556) The minuscule cost difference makes no >>>> difference to me. >>>> >>> >>>Can't comment, have never used it. My signal sources are generally >>>74HC14 or CD40106. You get six per package, dirt cheap. >>> >>>-- >>>Regards, Joerg >>> >>>http://www.analogconsultants.com/ >> >>555 is frequency stable versus supply voltage, that is its big plus. > >--- >Only 1%/V at Vcc = 5V, but it tempco is 50ppm at Vcc = 5V
If you use the RC arrangement on the data sheet. If you feedback from the output, as I've shown on several occasions, the TC is essentially as good as the TC's of the external components.
>--- > >>I use 4046 because it has a VCO frequency control DC input. > >--- >555 does too, but it's nowhere near as nice as the 4046's
...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Dec 23, 2:29=A0pm, Joerg <inva...@invalid.invalid> wrote:
> George Herold wrote: > > Hey, I think I=92ve got a use for a few dual 555 timers. > > (First time in ~20 years) > > I want to make some signal sources with a max freq. of maybe 100kHz. > > (I figure I=92ll heavily RC filter the output) > > I was going to order the CMOS version (TS556). =A0Is there any reason t=
o
> > use the TTL one? =A0(NE556) =A0The minuscule cost difference makes no > > difference to me. > > Can't comment, have never used it. My signal sources are generally > 74HC14 or CD40106. You get six per package, dirt cheap. > > -- > Regards, Joerg > > http://www.analogconsultants.com/
I consideded the double inverter circuit, but I was thinking of using the triangle wave 'output' from the 555. I was also thinking of an integrating opamp feeding a comparator feeding the back to opamp through a resistor. George H.