OK. I take it you have this built up with PSUs etc.
Is this originally an EasyPCB file? That would make things easier.
Do the component numbers on the schematic match your eBay unit?
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What's the maximum voltage that WTpro gives out?
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Did you mean "square wave with any fidelity." ?
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If your TDA chip amp design is stable, that would be a good starting point for a chip amp current source.
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80 ohms is no where near enough. In addition the F1 is 5% THD at 9 watts. You would not be able to measure the linearity of the speaker with this amp.
Just sharing my desktop amp since it's on topic here. Repurposed from a late 60's Sears under dash 8-track. A few small mods and this little amp became extremely enjoyable to listen to.
Measurements were taken with the speakers as load not a resistor. Easily spotted is the peak at 240Hz, the resonance of my speakers.
Measurements were taken with the speakers as load not a resistor. Easily spotted is the peak at 240Hz, the resonance of my speakers.
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These are very interesting. however, the voltage limit is much too low on these amplifiers. They are intended to develop massive current into almost a dead short.
I noticed that. What voltage swing do you need ?
Perhaps one of those type amps with a good transformer ?
Woofer, I sent you a PM asking for your email address. I'd like to send you a draft proposal for a WTpro Transconductance Amp using ChipAmps.
I'm not sure if we can use a simple resistor in the earthy lead of the speaker to get Current Drive with WTpro. I think you said WTpro current measurement required a resistor to earth.
Can you post a sketch of how you connect your supadupa current source amp with WTpro?
I'm not sure if we can use a simple resistor in the earthy lead of the speaker to get Current Drive with WTpro. I think you said WTpro current measurement required a resistor to earth.
Can you post a sketch of how you connect your supadupa current source amp with WTpro?
The WTPro has a shunt to ground. If a chipamp is used in a grounded shunt configuration, the signal across the shunt can be buffered and brought out to replace the shunt used in the WTPro. The WTPro shunt is mounted outside and is removable.
If a Howland current pump is employed, there will be two shunts in the system which will wast a little bit of voltage swing but no big deal in the grand scheme.
If a Howland current pump is employed, there will be two shunts in the system which will wast a little bit of voltage swing but no big deal in the grand scheme.
A "small" amp should be able to do 28V RMS and 2A RMS. The "big one" I had built does 48V RMS and 4A RMS.
The transformer is an interesting idea. I do not think it is a workable solution because of several reasons.
1. Hysteresis/distortion
2. phase problems
3. It blocks DC
1) Very little distortion if transformer is carefully chosen.
2) See 1
3) Why do you need to pass DC ?
(Re can be measured at a lower current
(lest you burn the VC))
I really think you'd get better results from
professionally made test equipment, rather than
something hacked together with TDA whatever.
To avoid the sensing resistor being connected to ground, Merilainen suggests (in his book pp 190-191) to insert it between the power amp output and the load, the voltage across it being sensed by an op-amp (NE5534) in differential mode. The output of this op-amp is connected to the inverting input of the power amp and a Zobel RC is added across the load.
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Nobody makes an off-the-shelf amp I need.
DC bias is useful to look at T/S parameters vs DC offset. It is a way to find voice coil offset. Also being able to plot excursion vs current at 1Hz is useful. There is a great AES article on using an accelerometer to find Qt at high excursion.
Creating a DIY amp of the kind I am envisioning will be useful for hobbyist loudspeaker enthusiasts. Most of my customers are loudspeaker DIYers.
Most useful products started out as a hacked prototype. The first WT was a hack on my bench to replace a pile of test equipment and save me tons of time.
That is on my list of things to try. Do you think it practical to develop a box to implement the idea you describe? You could use the box with any generic amp to make it force current.