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my RTL memory circuit is an oscillator? please help! Answered

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Today I soldered together a "D-latch" one bit memory circuit comprised entirely of resistors and transistors. If someone asks me about the schematic, I'll post it.
The weird thing about my RTL (resistor transistor logic) memory circuit is that it also works as an oscillator that short circuits my power supply. There is also a slight delay between when i try to set my D-latch's memory state, and when it actually happens. 
I have an educated guess that the delay in state change is caused by whatever bizarre mistake caused the oscillation within the circuit.

does anyone know of any resistor transistor timer circuits on the web? that may help quite a bit. (lol. EPIC memory pun)

the picture above is my device.

the oscillation is around 1.2 Hertz. it occurs when the D (data) input of my memory circuit is high.

as you can see, this is really confounding me. please help with a comment!

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jensenr30 (author)2011-04-20

i found my mistake.
it was that i failed to put a 10Kohm resistor in series from data to the input of the not gate of the memory circuit.

I will be posting Instructables on how to make my version of the RTL d-latch memory bit. I will also be posting inst'ables on how to make more RTL gates soon! subscribe to see them!

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icengBest Answer (author)2011-04-19

Nice Packing, it could be a solder ball, or with apology a mistake of wiring.

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steveastrouk (author)iceng2011-04-20

Yes, a really neat little job.

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steveastrouk (author)2011-04-19

Can't say anything much without a schematic. Odds on, your output stage isn't working properly, and is conducting through itself rather than one or the other.

DON'T make the circuit bigger- thats a sure fire way to make it worse.

Put a 100uF cap, in parallel with a 100nF cap across the supply pins - always good practice anyway.

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jensenr30 (author)steveastrouk2011-04-21

"Can't say anything much without a schematic. Odds on, your output stage isn't working properly, and is conducting through itself rather than one or the other." --you

explain what you mean when you say the phrase "output stage"

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iceng (author)jensenr302011-04-22

Since you are going to join us ( be an EE ), I may tell you.
The "output stage" refers to the final functional part of a circuit.
I first ran across the term in the audio realm where the speaker driving circuitry of an audio amplifier is called the output stage.
The pre-amplifier would be considered the input stage.

A

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steveastrouk (author)jensenr302011-04-22

Dunno. Show the circuit diagram and I can tell you.

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steveastrouk (author)2011-04-20

How come you Best answered an answer that was completely wrong ?

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jensenr30 (author)steveastrouk2011-04-21

you bring up a good point.
At the time of picking the best answer, I really should have thought through the decision more. To be honest, I was really eager to get back to my d-latch project.

After reviewing the answers I found that iceng's answer was the best given. in fact, i now realize that his answer was the closest answer that i could get considering the amount of info given by me.
Thank you, iceng.

And sorry to MROHM for hastily making my decision. It was a decision that was rightly pointed out to be false.

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robot1398 (author)2011-04-20

schematic please i wanna make it too

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AndyGadget (author)2011-04-20


I can't see any decoupling capacitors on there.  They are necessary to stop switching spikes causing undesired triggering which could be what's happening.  As Steve says, you need a 100uF and a 0.1uF across the supply. 

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MROHM (author)2011-04-19

Schematic please!! Do You have .1ufd capacitor across Power Supply??( Reduces the effect of Oscillation!!) No Offense but your Circuit is Far Too Compressed!!! Build your Circuit on a BIGGER piece of Perfboard!!! Because this Board so compact You could be creating :FEEDBACK LOOPS: which is causing your circuit to break into OSCILLATION(undesirable at this stage of the game!!! So in Summary 1) Use~~.1ufd Capacitor across Power Supply. 2) Build Circuit on a bigger piece of perf or vero board 3) keepall wire connections Direct and NOT overlapping each other!! 3)Try NOT having Components(resistors) Touching each other!! Good Luck and Go Get IT!!!! I had a similar problem a few years ago and I'm giving you my 2 cets worth of information!! Please take all my Suggestions as Positive+++++ Criticism!!! I gotta go now I smell my Soldering Iron heating up!!! ( cets==== cents!!!)

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