Hi guys, I have an old vintage HP audio osciallator which I want to use for some experimentation to get more practice in electronics. Its output is continually variable between 4 and 20 volts. Problem is, for some experiments I have in mind, I need it to output only between 1mV and 10mV. The oscailator's output impedance is 600 ohms it states. Can anyone suggest a simple passive attenuator I could build from easily available components which would give me this much lower output please? thanks!
Audio Attenuator
Started by ●June 8, 2021
Reply by ●June 9, 20212021-06-09
Chris M. White wrote:> Hi guys, > > I have an old vintage HP audio osciallator which I want to use for > some experimentation to get more practice in electronics. Its output > is continually variable between 4 and 20 volts. Problem is, for some > experiments I have in mind, I need it to output only between 1mV and > 10mV. The oscailator's output impedance is 600 ohms it states. > Can anyone suggest a simple passive attenuator I could build from > easily available components which would give me this much lower output > please? > thanks! >A bit more detail would be useful. However, something like a resistive voltage divider will probably be a good place to start. 10k GEN 0----RRRRR----*----0 OUT | R R 10 ohms R | | GND To get down to 1 mV, you can hang a pot on the output. Figuring out just how to do that would be a step forward. Cheers Phil Hobbs
Reply by ●June 9, 20212021-06-09
On 2021-06-08, Chris M White <cw9877@gsm.com> wrote:> Hi guys, > > I have an old vintage HP audio osciallator which I want to use for > some experimentation to get more practice in electronics. Its output > is continually variable between 4 and 20 volts. Problem is, for some > experiments I have in mind, I need it to output only between 1mV and > 10mV. The oscailator's output impedance is 600 ohms it states. > Can anyone suggest a simple passive attenuator I could build from > easily available components which would give me this much lower output > please? > thanks!a simple resistive divider will give a fixed ratio reduction in amplitude, unfortunately that won't cover the whole 10:1 range you want as your input only has 5:1 adjustment. You could use a potentiometer to make an adjustable attenuator and get a variable reduction that way. -- Jasen.
Reply by ●June 9, 20212021-06-09
On Wed, 9 Jun 2021 04:06:44 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>Chris M. White wrote: >> Hi guys, >> >> I have an old vintage HP audio osciallator which I want to use for >> some experimentation to get more practice in electronics. Its output >> is continually variable between 4 and 20 volts. Problem is, for some >> experiments I have in mind, I need it to output only between 1mV and >> 10mV. The oscailator's output impedance is 600 ohms it states. >> Can anyone suggest a simple passive attenuator I could build from >> easily available components which would give me this much lower output >> please? >> thanks! >> > >A bit more detail would be useful.I'm happy to oblige. Anything specific?> >However, something like a resistive voltage divider will probably be a >good place to start. > > > 10k >GEN 0----RRRRR----*----0 OUT > | > R > R 10 ohms > R > | > | > GND > >To get down to 1 mV, you can hang a pot on the output. Figuring out >just how to do that would be a step forward.What's the problem in that? Seems simple enough to my simple mind!
Reply by ●June 9, 20212021-06-09
On 6/9/21 11:24 AM, Chris M. White wrote:> On Wed, 9 Jun 2021 04:06:44 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> Chris M. White wrote: >>> Hi guys, >>> >>> I have an old vintage HP audio osciallator which I want to use for >>> some experimentation to get more practice in electronics. Its output >>> is continually variable between 4 and 20 volts. Problem is, for some >>> experiments I have in mind, I need it to output only between 1mV and >>> 10mV. The oscailator's output impedance is 600 ohms it states. >>> Can anyone suggest a simple passive attenuator I could build from >>> easily available components which would give me this much lower output >>> please? >>> thanks! >>> >> >> A bit more detail would be useful. > > I'm happy to oblige. Anything specific?What's the load? Any DC involved?> >> >> However, something like a resistive voltage divider will probably be a >> good place to start. >> >> >> 10k >> GEN 0----RRRRR----*----0 OUT >> | >> R >> R 10 ohms >> R >> | >> | >> GND >> >> To get down to 1 mV, you can hang a pot on the output. Figuring out >> just how to do that would be a step forward. > > What's the problem in that? Seems simple enough to my simple mind! >Well, if you understand pots, you understand voltage dividers already. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com
Reply by ●June 9, 20212021-06-09
Chris M. White wrote: -----------------------------> > >A bit more detail would be useful. > I'm happy to oblige. Anything specific?** What old HP have you got? Sure it has not been modified to get only 4-20V out ? Seems weird otherwise. ..... Phil
Reply by ●June 10, 20212021-06-10
On Wed, 9 Jun 2021 11:37:00 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 6/9/21 11:24 AM, Chris M. White wrote: >> On Wed, 9 Jun 2021 04:06:44 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> Chris M. White wrote: >>>> Hi guys, >>>> >>>> I have an old vintage HP audio osciallator which I want to use for >>>> some experimentation to get more practice in electronics. Its output >>>> is continually variable between 4 and 20 volts. Problem is, for some >>>> experiments I have in mind, I need it to output only between 1mV and >>>> 10mV. The oscailator's output impedance is 600 ohms it states. >>>> Can anyone suggest a simple passive attenuator I could build from >>>> easily available components which would give me this much lower output >>>> please? >>>> thanks! >>>> >>> >>> A bit more detail would be useful. >> >> I'm happy to oblige. Anything specific? > >What's the load? Any DC involved?No DC and very high impedance load (> 1M ohm)>> >>> >>> However, something like a resistive voltage divider will probably be a >>> good place to start. >>> >>> >>> 10k >>> GEN 0----RRRRR----*----0 OUT >>> | >>> R >>> R 10 ohms >>> R >>> | >>> | >>> GND >>> >>> To get down to 1 mV, you can hang a pot on the output. Figuring out >>> just how to do that would be a step forward. >> >> What's the problem in that? Seems simple enough to my simple mind! >> > >Well, if you understand pots, you understand voltage dividers already.My main concern was not to draw too much from the already quite high impedance (600 ohms) of the source generator. Did you allow for that in the values you came up with?
